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LIBRARY OF CONGRESS. 



Shelf J3»I7~ 

UNITED STATES OF AMERICA. 



GUIDE 



STUDY OP COMMON PLANTS 



AN INTRODUCTION TO BOTANY 



BY 



VOLNEY M. SPALDING 

Professor of Botany in the University of Michigan 



BOSTON, U.S.A. 
D. C. HEATH & CO., PUBLISHERS 




1893. 



N~ 



Copyright, 1893, 
By YOLNEY M. SPALDING. 



Typography by J. S. dishing & Co. 
Presswork by S. J. Parkhill & Co. 



PREFACE. 



These exercises have been prepared for classes in high 
schools and other institutions of similar grade, and are 
intended to indicate, in a general way, the nature of the 
work that in the judgment of the writer should be under- 
taken with young people who are just beginning the sys- 
tematic study of common forms of plant life. They were 
suggested by frequent inquiries of teachers regarding the 
preparation in botany now required for admission to the 
University of Michigan. 

No originality is claimed for the subject-matter or its 
treatment, although much time has been spent in the 
effort to develop a natural and practicable method of 
approaching the study of living things. While the study 
of relationship holds the first place, the attention of the 
pupil is directed at every step to the physiological signifi- 
cance of observed facts; and although this will hardly be 
approved by those who attempt to separate sharply the 
domain of morphology from that of physiology, it has 
seemed to the writer better to follow Nature than be 
cramped by such artificial barriers. Some of the exer- 
cises will perhaps appear too simple and others too diffi- 
cult, but a judicious selection on the part of the teacher 
will do much to correct this. 

As to the ground that ought to be covered in such a 
course, and the proper sequence of subjects, there is natu- 



iv PREFACE. 

rally great difference of opinion among practical teachers. 
Theoretically it would seem best to begin with the lowest 
forms of plants, and work up to the higher; but after 
careful consideration, and in view of the actual state of 
things in most of our preparatory schools, a different plan 
has been adopted. 

It is hoped that in spite of mistakes and imperfections, 
sure to be brought to light if the book is used, it may never- 
theless prove serviceable to a rapidly increasing number 
of teachers who are desirous of improving existing methods 
of instruction. To Dr. Erwin F. Smith of Washington, 
D.C., and Miss Efne A. Southworth of Barnard College, 
who have kindly read the proofs throughout ; to Mr. 
W. H. Rush of the University of Michigan, who has criti- 
cally reviewed and tested the practical directions; and 
to others who have aided in various ways, the sincere 
thanks of the writer are due. 



CONTENTS. 



PAGE 

To the Student ix 

To the Teacher xii 

Works of Reference ......... xv 

Laboratory and Permanent Outfits ...... xix 

ORGANS OF FLOWERING PLANTS. 

I. Seeds 1 

II. Growth of Plants from the Seed. .... 20 

III. Root . . 29 

IV. Stem 38 

V. Leaf 57 

VI. Flower 74 

VII. Fruits x 88 

NATURAL GROUPS OF PLANTS. 1 

VIII. ALG^E 96 

IX. 3IUSCINE^E 105 

X. FILICINEiE 114 

XI. EQUISETINE^E 123 

XII. LYCOPODINE^E 127 

1 Groups above families have been placed in boldface type without attempting their 
coordination. 

V 



VI 



CONTENTS. 



GYMNOSPERMS. 



XIII. COXIFER^E 



PAGE 
132 



MONOCOTYLEDONS. 

XIV. Graminejs 137 

XV. Cyperace^e 141 

XVI. Arace.e 144 

XVII. Liliace.e 148 

XVIII. Amaryllidace/E ....... 150 

XIX. Iridace^e 152 

XX. OrchidacExE 155 



DICOTYLEDONS. 



XXI. 


Salicace^e . 


XXII. 


RANUNCULACEiE 


XXIII. 


Crucifer^: . 


XXIV. 


Rosacea 


XXV. 


Leguminos^e 


XXVI. 


Geraniace^e 


XXVII. 


Euphorbiace^e 


XXVIII. 


ACERACE^E . 


XXIX. 


Malvaceae . 


XXX. 


VlOLACE^E . 


XXXI. 


Oxagrace^e 


XXXII. 


Umbelliferje 


XXXIII. 


ASCLEPIADACE^E 


XXXIV. 


BORRAGINACEiE 


XXXV. 


Labiatve 



161 
164 
171 
174 
177 
181 
186 
190 
193 
196 
200 
203 
208 
212 
215 



CONTENTS. yil 

PAGE 

XXXVI. SOLANACE^E . . / 219 

XXXVII. Scrophulariace^ 223 

XXXVIII. Caprifoliaceze . 228 

XXXIX. CuCURBITACEiE ........ 231 

XL. Composite . . 235 



TO THE STUDENT. 



You are beginning the study of living things, and it is 
very important that you should begin in the right way. 
These practical exercises are intended to help, you, but not 
to do the work for you. Many of the exercises will seem 
very simple, but if you actually do what is called for, it 
will be plain why so much stress is laid on knowledge 
gained by direct personal observation and experiment. 1 

There are a few things that you ought to consider at the 
outset. 

1. First of all, it is essential that you should learn to 
see things just as they are, and to report exactly what 
you have seen. Agassiz used to say to his students : 
" Study to know what is; be courageous enough to say 
' I do not know.' " Tyndall said to the teachers at South 
Kensington : " In every one of your experiments endeavor 
to feel the responsibility of a moral agent. ... If you 
wish to become acquainted with the truth of Nature, you 
must from the first resolve to deal with her sincerely." 
Darwin in his autobiography 2 writes: " I had during many 

1 " You wish, for example, to get a knowledge of magnetism ; well, pro- 
vide yourself with a good book on the subject, if you can, but do not be 
content with what the book tells you ; do not be satisfied with its 
descriptive woodcuts ; see the actual thing yourself. Half of our book- 
writers describe experiments which they never made." — Tyndall, Frag- 
ments of Science. 

2 Life and Letters, p. 71. 



X TO THE STUDENT. 

years followed a golden rule, namely, that whenever a 
published fact, a new observation or thought, came across 
me, which was opposed to my general results, to make a 
memorandum of it without fail and at once, for I had 
found by experience that such facts and thoughts were far 
more apt to escape from the memory than favorable ones." 

2. When you have seen a thing clearly, be sure to express 
your conception, whether by drawing, or written descrip- 
tion, or both, as accurately as possible. Learn to use 
scientific language with precision. Write out your obser- 
vations in full, in the best English at your command. 
Avoid abbreviations and every other device for saving 
time. Make your drawings so that an engraver could 
copy them. Do not hesitate to do your work all over 
again, if it can be improved, as it probably can be, and do 
not leave a thing until you have not only a complete obser- 
vation, but a complete expression of it. 

3. Do not be hasty in drawing conclusions. Make a 
constant practice of comparing the object you are studying 
with others of the same kind. Note differences and resem- 
blances. Learn by the actual process what it is to acquire 
a general conception. " Honesty in science means, first, 
facts well proved, and then conclusions slowly and pain- 
fully deduced from facts well proved." 1 In all your 
work stop and think. The mere accumulation of facts, 
if nothing is done with them, is of little consequence. 
Constantly ask the question, what does this fact mean ? 
You may or may not be able to answer the question, but 
that is no reason for not raising it. 

4. Cultivate self-reliance, but not self-sufficiency. Study 

1 J. P. Lesley, Presidential Address, Am. Assn. for the Advancement 
of Science, 1885. 



TO THE STUDENT. XI 

things themselves rather than book descriptions of them, 
but habitually use the books you are referred to, compar- 
ing point by point your own observations with what the 
authors have to say. The writers cited may or may not 
be right ; they are more likely to be than you are ; but 
both of you may be wrong. The best way is to observe for 
yourself, then consult the books ; then observe again, and 
continue your observations and comparisons until the exact 
truth is ascertained. This is the way investigations are 
conducted, and you are learning how to investigate. 

5. This leads to a word on the use of books. Make it 
a regular practice to look up the references that are given 
with the exercises. By doing this you will not only 
become acquainted with some of the most valuable botan- 
ical literature, but, what is more important, you will come, 
in some measure, to understand the habits and methods of 
the great workers in science, and will, perhaps insensibly to 
yourself, catch something of their spirit, and learn to 
work as they did, honestly, accurately, and " with infinite 
patience." 

One of the greatest investigators who has ever lived 
wrote a few years ago : " Whenever I have found out that 
I have blundered, or that my work has been imperfect, 
and when I have been contemptuously criticised, and even 
when I have been over-praised, so that I have felt morti- 
fied, it has been my greatest comfort to say hundreds of 
times to myself that ; I have worked as hard and as well 
as I could, and no man can do more than this.' " 1 

1 Charles Darwin, Life and Letters, p. 72. 



TO THE TEACHER. 



MATERIAL AND METHODS. 



In order to use these exercises successfully it will be 
necessary to adopt the laboratory, as distinguished from 
the text-book, method of instruction. The practice, still 
too common, of using ordinary recitation seats and benches 
for work of this kind is extremely unsatisfactory, and 
ought to be abandoned. The best arrangement is to have 
places assigned at long tables — one table in front of each 
window, so that every student can have a full amount of 
light. North, east, and west windows are preferable, those 
on the north side being the best. In every case the pupil 
is to be provided with the material called for, and this 
should be typical of its kind and sufficient in quantity. 
In a large proportion of the exercises the plants needed 
are common everywhere and easily obtained. When it is 
impossible to procure them the exercise is to be omitted. 
It has no significance whatever unless the thing talked 
about is actually present to the eye. It will generally be 
found better to secure an appropriation of a few dollars 
and employ some one regularly to furnish a supply of 
material than to depend on what the teacher and members 
of the class can gather. In any case the things to be 
studied must be systematically provided. They cost far 
less, but are just as essential as the reagents and apparatus 
in a chemical or physical laboratory. 



TO THE TEACHER. Xlll 

Too much emphasis cannot be laid on the importance 
of securing at the outset a fairly complete equipment. 
The necessity of following the laboratory method in science 
teaching is now so universally recognized that it is to be 
hoped that boards of education will generally adopt the 
better way and cheerfully pay for it. Having once secured 
the necessary tables, instruments, and books, the expense 
from year to year is extremely small in comparison with 
the result aimed at, viz. a discipline that can be attained in 
no other tvay. 

The use of the microscope, methods of sectioning, 
mounting microscopic objects, drawing, and other prac- 
tical operations of the laboratory are best learned of the 
living teacher. Useful suggestions, however, will be found 
in the excellent handbooks of Strasburger, Arthur, Barnes, 
and Coulter, and other laboratory manuals. 

DISPOSITION OF TIME. 

When practicable, it is much more advantageous to 
arrange the time given to laboratory work so that each 
student can work two consecutive hours for a certain num- 
ber of days each week. When this cannot be done with- 
out seriously interfering with the school programme, the 
following plan is suggested: Give four hours each week 
to practical exercises, requiring each member of the class 
to work independently in his own place, precisely as he 
would at a table in a chemical laboratory, the teacher pass- 
ing from table to table, giving personal help as it is needed, 
and from time to time giving notes and directions to the 
class as a whole. The remaining hour, say on Friday or 
Monday, or sometimes both, may be used for recitations, 
reports on laboratory work, and the dictation of notes and 



xiv TO THE TEACHER. 

references. Exercises to be conducted out of school hours 
may be assigned at the discretion of the teacher, but 
generally it will be found that the best work is done in 
the laboratory under his personal direction. 

In the majority of preparatory schools half a year is 
given to botany. It is very desirable that the time should 
be extended, but until this is done it is recommended 
that the exercises be followed substantially as here out- 
lined, with the omission of a part, or possibly the whole, of 
the microscopic work. If the latter is undertaken, and a 
reasonable amount of time is given to the study of different 
families of plants in the spring, a full year will be needed. 



WORKS OF REFERENCE. 



In connection with the exercises, frequent references 
are given. In a few cases books of a more or less popular 
character are mentioned, and some of the most important 
works in French and German are referred to, inasmuch 
as they are well-nigh indispensable to the teacher. In 
general, the works named are easily obtained, and ought to 
have a place in any respectable school library. Several 
copies of the books in constant use should be placed on 
tables in the laboratory, where they can be consulted with- 
out loss of time, the students being given to understand 
that they are expected to look up references as habitually 
and critically as they would if reading a classical author. 
One or more of the best periodicals may properly be 
included in the essentials of the laboratory outfit. The 
following list, by no means complete, includes some of the 
most generally useful botanical works. 

LABORATORY MANUALS. 

Arthur, Barnes, and Coulter, Plant Dissection. Henry Holt & Co., New 

York, 1886. 
Bower and Vines, Practical Botany, Parts I. and II. Macmillan & Co., 

London, 1885 and 1887. 
Clark, Practical Methods in Microscopy. D. C. Heath & Co., Boston, 1893. 
Strasburger and Hillhouse, Practical Botany. Macmillan & Co., New 

York. 1889. 

These manuals are of the utmost value as laboratory guides. 

The first is the simplest, and, on the whole, most suitable for 

xv 



XVI WORKS OF REFERENCE. 

beginners. The third contains the latest and most approved 
methods of microscopical manipulation. The last is most com- 
plete, and gives the modern methods of work with such clearness 
and detail as to render it indispensable in every botanical labo- 
ratory. The original work of which it is a translation [Stras- 
burger, Das Heine botanische Praktikum. Fischer, Jena] will be 
preferred by those who read German. 

STRUCTURAL AND PHYSIOLOGICAL. 

Gray, Structural Botany (sixth edition). Ivison, Blakeman & Co., New 
York, 1879. 

Goodale, Physiological Botany. Ivison, Blakeman & Co., New York, 
1885. 

Bessey, Botany. Henry Holt & Co., New York, 1888. 

DeBary, Comparative Anatomy of the Phanerogams and Ferns. Oxford, 
Clarendon Press, 1884. 

Vines, Physiology of Plants. Cambridge, University Press, 1886. 

Sachs, The Physiology of Plants, Trans, by H. Marshall Ward. Oxford, 
Clarendon Press. Macmillan & Co., 1887. 

Haberlandt, Physiologische Pfanzenanatomie. Engelmann, Leipzig, 
1884. 

Frank, Lehrbuch der Pflanzenphysiologie. Parey, Berlin, 1890. 

Zimmermann, Die Morphologic und Physiologie der Pflanzenzelle . 
Trewendt, Breslan, 1887. 

Detmer, Das pflanzenphysiologische Praktikum. Fischer, Jena, 1888. 

Detmer, Manuel technique de Physiologie vegetale. C. Reinwald, Paris, 
1890. Translation of the last-named work revised and extended 
by the author. 

Bessey 's Botany is the least expensive book that covers the 
ground at all satisfactorily. With Gray's Structural and Good- 
ale's Physiological Botany one is better equipped for work, inas- 
much as the whole general subject of organography and physiology 
is ably and clearly presented in them. Sachs' Lectures on the 
Physiology of Plants is indispensable. 

MORPHOLOGICAL AND SYSTEMATIC. 

Goebel, Outlines of Classification and Special Morphology of Plants. 

Oxford, Clarendon Press, 1887. 
Luerssen, Handbuch der Systematischen Botanik. Haessel, Leipzig, 1879. 



WORKS OF REFERENCE. XV11 

Eichler, Bluthendiagramme. Engelmann, Leipzig, 1875. 

Engler und Prantl, Die natiirlichen Pflanzenfamilien. Engelmann, 

Leipzig. 

All of these are of great value, especially the rather expensive 

work of Engler and Prantl, now in course of publication. 

FLORAS. 

Gray, Manual of Botany (sixth edition). Ivison, Blakeman & Co., 
New York. 

Chapman, Flora of the Southern United States (second edition). Ivi- 
son, Blakeman & Co., 1883. 

Coulter, Manual of the Botany of the Rocky Mountain Region. Ivison, 
Blakeman & Co., 1885. 

Coulter, Manual of the Phanerogams and Pteridophytes of Western 
Texas. U. S. Dept. Agric, 1892. 

Gray, Synoptical Flora of North America. (In progress.) 

Gray's Manual is commonly bound with the " Lessons " in one 
volume, but may be had separate in convenient form for the 
pocket. Dr. Gray's final revision of the "Lessons " has been pub- 
lished under the title, Elements of Botany. Ivison, Blakeman & 
Co., 1887. 

CRYPTOGAMIC BOTANY. 

Eaton, Ferns of North America. Cassino, Boston, 1879. 

Lesquereux and James, Mosses of North America. Cassino, Boston, 

1884. 
Farlow, Marine Algce of New England. U. S. Fish Commission, 

Washington, 1881. 
Tuckerman, North American Lichens. Cassino, Boston, 1882. 
DeBary, Comparative Morphology and Biology of the Fungi, Mycetozoa, 

and Bacteria. Oxford, Clarendon Press, 1887. 
v. Tavel, Vergleichende Morphologie der Pilze. Fischer, Jena, 1892. 
Bennett and Murray, Handbook of Cryptogamic Botany. Longmans, 

Green & Co., London and New York, 1889. 
Plo wright, British Uredinece and Ustilagineoz. Kegan Paul, Trench & 

Co., London, 1889. 
Underwood, Our Native Ferns and their Allies. Bloomington, 111., 

1882. 



XV111 WORKS OF REFERENCE. 

The list of works on Cryptogamic Botany might be greatly 
extended. Numerous references to the literature of the algae 
will be found in Farlow's work mentioned above, and to that of 
the fungi in DeBary's treatise. For other references consult Ben- 
nett and Murray's Handbook. 

GENERAL. 

Miiller, The Fertilization of Flowers. Macmillan & Co., London, 1883. 
DeCandolle, Origin of Cultivated Plants. Appleton & Co., New York, 

1885. 
Kerner, Flowers and their Unbidden Guests. Paul & Co., London, 1878. 
Darwin, Insectivorous Plants, and other works. Appleton & Co., New 

York. 
Lubbock, Seedlings. Appleton & Co., New York, 1892. 
Lubbock, Flowers, Fruits, and Leaves. Macmillan & Co., London, 

1886. 
Goodale, Wild Flowers of America. Cassino, Boston, 1882. 
Sachs, History of Botany. Macmillan & Co., 1890. 
Lindley and Moore, The Treasury of Botany. Longmans, London, 

1874. 
Kerner von Marilaun, Pflanzenleben, 2 vols. Bibliographisches Insti- 

tut, Leipzig and Vienna, 1891. 

Miiller's work on the Fertilization of Flowers gives references 

to the immense and increasing body of literature on this subject. 

Kerner's work is out of print, but may occasionally be picked up, 

and is a most charming little book. All of Darwin's books 

should have a place in such a list. 

CURRENT LITERATURE. 

The Botanical Gazette. Lake Forest, 111., $2.50 per year. 

Bulletin of the Torrey Botanical Club. New York, §2.00 per year. 

Annals of Botany. Oxford, Clarendon Press. 

Botanisches Centralblatt. Gotthelft, Cassel. 

The Botanical Gazette and Torrey Bulletin are well-known Ameri- 
can journals. The Annals of Botany is a new periodical of a 
high order, with original monographs, criticisms of current lit- 
erature, etc. The Botanisches Centralblatt is indispensable in 
botanical research. 



LABORATORY AND PERMANENT OUTFIT. 



1. The laboratory should be a large room, properly 
ventilated, with as many windows as practicable, and used 
exclusively as a laboratory. An upper room is preferable 
to a lower one, since the air is clearer and there is less 
liability to disturbance from passers-by. 

2. The laboratory tables should be plain and solid, 
oiled, but not painted or varnished, and large enough to 
give each student all the space he requires without crowd- 
ing. Drawers should be placed in the tables, or in a 
separate case, in which the students' outfit may be kept. 

3. Receptacles for waste materials, conveniently 
placed and frequently emptied, and plenty of clean 
water are indispensable. 

4. A pair of balances, such as are employed by drug- 
gists for accurate weighing, will be required. 

5. Microscopes. For the compound microscope, the 
so-called continental stand is preferable, on account of its 
simplicity, firmness, and convenient size. Two good objec- 
tives, | and i inch, or their equivalent, and two eye-pieces 
are necessary. Such an instrument may be purchased of 
a reliable dealer for about $30. It will hardly be practi- 
cable to equip the laboratory with lower-priced ones that 
will prove satisfactory. 

Dissecting microscopes of simple construction are needed, 



XX LABORATORY AND PERMANENT OUTFIT. 

but a good hand-lens, properly mounted, will answer the 
same purpose. See Arthur, Barnes, and Coulter, Plant 

Dissection, p. 2. 

6. Glassware and miscellaneous articles. A stock of 
common plates and bowls, beakers, glass tubing, bell-jars, 
test-tubes, metric rules, etc., will be required, but are best 
purchased as needed, at the discretion of the teacher. 

REAGENTS. 

Of the reagents most employed in botanical work the 
following are required : 1 — 

7. Alcohol. For preserving plant-tissues, except in 
cases involving the most delicate operations, three grades 
of alcohol are all that will be needed. The lowest grade 
(between 45 and 50 per cent) is composed of equal parts 
of alcohol of commerce and distilled water. The inter- 
mediate grade (between 70 and 75 per cent) is prepared 
by adding 25 parts of distilled water to 75 parts of 
commercial alcohol. The highest grade is the alcohol of 
commerce (approximately 95 per cent). 

Parts of plants to be preserved are allowed to remain 
24 hours in the lowest grade of alcohol, then for the same 
length of time in alcohol of intermediate strength, and 
finally are placed in 95 per cent alcohol, in which they 
may be kept indefinitely. It is necessary to guard against 
attempting to preserve too much material in a given 
quantity of alcohol, as decomposition is likely to take 
place. 

1 Reference may be made to various works in which reagents and 
methods are discussed at much greater length. Among these are Stras- 
burger and Hillhouse, Practical Botany ; Behrens, Guide to the Use of 
the Microscope in Botany ; Zimmermann, Die botanische Jlikrotechnik. 



LABORATORY AND PERMANENT OUTFIT. xxi 

8. Absolute alcohol. For finer histological work abso- 
lute alcohol and a larger number of grades of commercial 
alcohol more carefully prepared are necessary. 

9. Iodine solution. Distilled water 10 c.c, potassic 
iodide 1 gm., iodine 0.25 gm. Dilute to 250 c.c. 

10. Glycerine. Pure glycerine is employed in some 
cases, but equal parts of glycerine and distilled water will 
generally be found most serviceable. 

11. Schulze's solution. This may be prepared accord- 
ing to the rule given in Strasburger's Praktikum, but it 
will be found more convenient to employ Grubler's chlor- 
iodide of zinc, which may be obtained of Eimer and 
Amend, New York. 

12. Potash solution. One part of solid caustic potash 
dissolved in 20 parts of distilled water. This reagent 
attacks glass, and care should be taken to prevent its 
getting on the objectives. 

13. Glacial acetic acid. 

14. Sulphuric acid. 

15. Hydrochloric acid. 

16. Picric acid. 

17. Phloroglucin. One per cent alcoholic or watery 
solution. Employed with hydrochloric acid as a test 
forlignin. 

18. Picric aniline blue. Add picric acid to distilled 
water until a saturated solution is obtained. To this add 
slowly a saturated watery solution of aniline blue until it 
is of a deep blue-green color. 



XX11 LABORATORY AND PERMANENT OUTFIT. 

19. Acetic methyl green. To a 2 per cent solution 
of glacial acetic acid add methyl green until the solution 
is deeply colored. 

STUDENT'S OUTFIT. 

Each pupil should be provided with the following 
articles : 1 — 

20. A Coddington lens or achromatic triplet. Either 
of these will serve a good purpose. The cheap lenses, 
mounted in horn, and sold for a dollar or less, are of 
little use. A good Coddington lens may be purchased 
of Bausch and Lomb, Rochester, N.Y., for $2.50, and an 
excellent achromatic triplet of James W. Queen & Co., 
Philadelphia, for $ 4.75. 

21. A good pocket knife, kept sharp. 

22. Razor of good quality and medium size, hollow 
ground. The Torrey razor, manufactured at Worcester, 
Mass., is recommended. 

23. A pair of fine forceps. 

24. Slides and thin glass covers for mounting micro- 
scopic objects. The glass covers should be of medium 
thickness, and not less than ^ of an inch in diameter. 

25. Needles mounted in handles. 

26. CameFs-hair brushes of medium size. 

27. Note-book and drawing paper. The latter should 
be unruled, rather heavy, of good quality, and cut to a 
convenient size for drawings. 

1 In some cases it may be practicable, in order to save expense, for two 
to use the same outfit ; but the practice is not to be commended, except 
in case of necessity. 



LABORATORY AND PERMANENT OUTFIT. XX111 

28. Drawing* pencils and eraser. The pencils should 
be of at least two grades, medium and hard. 

If the student pays a laboratory fee, most of the 
articles named above should be furnished by the school 
board ; if no fee is charged, he may reasonably be required 
to purchase for himself those that are liable to loss or 
deterioration through use. 



STUDY OF COMMON PLANTS. 

I. SEEDS. 1 

MATERIAL REQUIRED. 

Common white beans. Other varieties, snch as " butter beans," etc. 

Peas, oats, wheat, Indian corn, — several varieties of the latter. 

Castor oil seeds. 

Seeds of white pine, Norway spruce, and other conifers. 

Commercial " nuts," such as chestnut, peanut, filbert, almond, Brazil 

nut, and English walnut. 
Seeds of coffee, date, flax, sunflower, tomato. 
As many kinds as possible of seeds with winged or hooked appendages 

or other special arrangements for dissemination. 
Seeds of squash, pumpkin, watermelon, muskmelon, cucumber, gourd, 

and similar collections from other important families. 

COMMON BEAN. Phaseolus vulgaris, Savi. 

I. Compare a number of white beans, and see if they are 
all alike. Select a good specimen. Observe and describe 

1. The shape, surface, and color. 

2. Surface markings : 

a. The scar, hilum, 2 marking the place where the 
seed was attached. 

1 General references: Gray, Structural Botany, pp. 305-314; Stras- 
burger, Practical Botany, Chaps. I and II ; Sachs, Physiology of Plants ; 
Haberlandt, Physiologische Pflanzenanatomie, pp. 277-293. 

2 If any of the terms are unfamiliar and are not sufficiently explained 
in the text, consult Webster's International Dictionary. 

1 



Z STUDY OF COMMON PLANTS. 

b. Near the hilum a minute orifice, micropyle, easily 

seen under a lens. 

c. The chalaza, the part where the seed coats blend 

with each other and nutriment enters the grow- 
ing seed. In this case the chalaza is located 
externally by a small protuberance near the 
hilum, on the opposite side from the micropyle. 

II. With a sharp penknife or needle remove the integ- 
ument, testa, from a bean that has been soaked in water 
for a day. Near the hilum a small pointed body, the 
radicle, will be found. Locate it accurately. Does it 
have any relation to the micropyle ? 

III. Separate the two halves, cotyledons. Examine 
under a good lens. Notice 

1. The form and position of the radicle. 

2. The delicate structure, plumule, connected with it. 
Draw the parts, taking care to represent accurately 

the leaves of the plumule and their venation. 

IV. Examine beans that have lain a few days on moist 
blotting paper under a bell-jar. What changes have taken 
place ? 

What part of the seed has developed into the primary 
root ? What changes has the plumule undergone ? 

V. With the common bean compare a number of other 
varieties, "butter bean," "scarlet runner," etc., noting 
carefully all points of likeness and difference. 

VI. Study next the common pea, comparing its struc- 
ture with that of the bean. 

VII. Write a detailed account of your observations of 
the bean and pea. Introduce drawings or outline sketches 



SEEDS. 6 

whenever the description will be rendered more intelligible 
by them. 

CASTOR OIL SEED. Ricinus communis, L. 

I. Study first the external features. 

1. Shape and surface. Compare different specimens as 

regards shades and distribution of color. 

2. Surface markings : 

a. The conspicuous, thickened protuberance at one 

end, the caruncle, a structure occurring in com- 
paratively few species. 

b. The string-like raphe, extending from the hilum 

(faintly seen at the edge of the caruncle) to 
the chalaza, near the other end. 

II. Remove the testa and observe the delicate inner 
seed coat, endopleura, enclosing the kernel. 

III. Split the kernel longitudinally, so as to expose the 
embryo. Examine under a dissecting microscope, or with 
a good lens. Draw the inner surface of one of the halves 
so as to show 

1. The outline and venation of the cotyledon. 

2. The short, straight radicle. 

3. The surrounding endosperm (tissue containing food 

material). 

IV. Record in detail what you have observed. Note 
important differences between the castor oil seed and com- 
mon bean. 

INDIAN CORN. Zea Mays, L. 1 

I. Study closely the external features of the grain. 
How do the two sides differ ? 

1 The grain of corn is really a seed-like fruit, in which the coats of 
fruit and seed are blended. Specimens for dissecting should be placed in 
water the day before they are to be used. 



4 STUDY OF COMMON PLANTS. 

II. With a sharp knife make a median longitudinal 
section perpendicular to the flat sides of the grain. Re- 
peat the process, if necessary, until a good specimen is 
secured. Observe on the cut surface 

1. The strong external membrane composed of the united 

coats of the fruit and seed. 

2. The endosperm, a tissue containing starch and other 

food materials, very hard in the dry grain, but 
easily cut in one that has lain some time in water. 

3. The embryo, with its conspicuous organ of absorp- 

tion, scutellum, the latter in close contact with the 
endosperm. 
Draw the section. 

III. Remove the entire embryo from a grain that has 
been soaked. Dissect out the parts enclosed in the 
scutellum. Compare them with the same parts as seen 
in section. Note 

1. The radicle pointing toward the small end of the 

grain, its end covered by the root-sheath. 

2. The caulicle, attached to the scutellum, and termi- 

nating above in 

3. The plumule. 

IV. Take a series of transverse sections and locate 
each one by comparing it with a longitudinal section. 
Repeat this until you are perfectly familiar with all the 
parts and their relative position. 

V. Study a grain of corn that has sprouted. What 
changes has the embryo undergone ? 

VI. Collect as many varieties of corn as you can and 
compare them. 



SEEDS. O 

VII. Study wheat in the same way that you have 
Indian corn, and compare the structure of the two grains. 
Compare oats with both. 1 In what respects are all three 
alike ? Point out the differences between them. 

VIII. Write a full account of your observations of these 
grains. Point out two important particulars in which 
they differ from peas and beans. 

SEEDS OF WHITE PINE. Pinus Strobus, L. 

I. Observe all the external features. Draw in outline a 
perfect specimen. Compare the seeds of Austrian pine or 
Norway spruce. 

II. Remove the testa, exposing the kernel enclosed in 
the delicate inner seed coat. 

III. Make both longitudinal and transverse sections of 
the kernel. Notice 

1. The form and position of the embryo. 

2. Around this the white, oily endosperm. Draw. 

IV. Remove the embryo and examine under a good 
lens. How do the two ends differ? How many coty- 
ledons are there ? 

V. Write a complete description. In what important 
particulars does the seed of the pine differ from those 
previously studied? 

PHYSIOLOGY OF SEEDS. 

Storage of Food. 

I. Cut through one of the cotyledons of a common 
bean and scrape the exposed surface lightly with the 

1 Cf. Arthur, Barnes, and Coulter, Plant Dissection, pp. 179, 180. 



STUDY OF COMMON PLANTS. 

point of a knife. Mount in water a very small portion 
of the powder thus obtained, and examine under a com- 
pound microscope, first with the low, and afterward with 
the high power. 

1. Numerous minute bodies are seen in the field of 

the microscope. These are grains of bean starch. 1 
Are they all of the same size ? Of the same 
shape ? Draw two or three of them. 

2. Focus carefully and study their structure. Are they 

homogeneous ? Compare different specimens in 
regard to this point. 

3. Run a small drop of iodine solution under the cover 

glass and observe the effect. Notice from the 
outside how far the reagent has advanced, then 
examine that part of the slide under the micro- 
scope, and see how differently the starch granules 
look after the iodine has acted upon them. 

II. Mount in the same way a bit of wheat flour taken 
from the inside of a grain of wheat. 

1. How do the starch grains compare with those of the 

bean in form, size, and structure ? Are the grains 
of wheat starch of uniform size ? 

2. Touch the cover glass lightly with a needle until 

some of the largest grains roll over. What is their 
shape? Draw a few grains in different positions 
so as to represent what you find to be charac- 
teristic. 

3. Test with iodine solution. 

III. Examine corn starch obtained in the same way 
from a grain of Indian corn. 

1 Useful suggestions for the microscopical examination of starch are 
given by Strasburger, Practical Botany, pp. 4-15. 



SEEDS. 7 

1. Compare the grains of corn starch with those of the 

bean and wheat. Draw. 

2. Test with iodine solution. 

IV. Cut a grain of oats in two, obtain some of the 
starch as directed in the preceding cases, and examine 
microscopically. The compound grains of starch present 
a widely different appearance from the simple ones of 
Indian corn, wheat, and beans. Study their structure 
carefully, and draw one or more. Test with iodine. 

From this and preceding observations what do you con- 
clude in regard to the usual form and structure of starch? 
What as to its reaction with iodine ? 

V. Cut a sunflower akene in two, and remove a small 
portion of the endosperm. Mount in water and apply 
slight pressure to the cover glass. Under the compound 
microscope numerous highly refractive drops of oil will be 
seen coming out of the broken tissue. Focus carefully on 
an oil drop, and observe its sharply defined border. What 
changes does it undergo as the focus is altered? 

Various other oily seeds, such as those of the squash, 
tomato, pine, English walnut, etc., may be studied in the 
same way. Enough of these should be examined to ensure 
familiarity on the part of the student with the appearance 
of fatty oil under the microscope. 

VI. Soak a date seed in water a day or more until it 
can be cut easily. Pare off a portion of it with a knife or 
scalpel, so as to expose a smooth, even surface, and then 
with a razor make extremely delicate sections of the endo- 
sperm. Mount some of these in glycerine, and others in 
Schulze's solution. Microscopic examination shows that 
the date seed consists chiefly of the greatly thickened 
walls of the cells that compose its substance. Watch the 



O STUDY OF COMMON PLANTS. 

action of Schulze's solution. The blue color that pres- 
ently appears indicates cellulose. 

VII. Examine similar sections of a coffee seed prepared 
and mounted in the same way. Notice how the cell walls 
differ from those of the date seed. 

VIII. Remove the testa of a castor oil seed, and cut 
a few thin sections from the endosperm. Mount in pure 
glycerine, and examine with the high power. 

1. The sections show (best on the edges where they are 

very thin) the cells of the endosperm filled with 
numerous rounded bodies. These are aleurone 
grains. They are of frequent occurrence in oily 
seeds, and constitute an important food substance. 

2. Draw a cell with its contents. Examine the aleurone 

grains closely, and see if you can detect any struct- 
ure. The small rounded body most frequently 
seen at one end of the aleurone grain is called a 
globoid. 

3. Run a drop of water under the cover glass and watch 

the effect. Some of the aleurone grains presently 
show, besides the rounded globoid, an angular 
crystalloid. 
Draw again a cell with its contents so as to show the 
changes that have taken place. 

4. After the water has had sufficient time to act on the 

cell contents, it is evident that they are becoming 

disorganized, and drops of oil are seen to have 

passed out of the section. 

Note. — It is important that all of these features should be sat- 
isfactorily made out before proceeding farther. It may be neces- 
sary to prepare a considerable number of slides, and possibly will 
require several hours. The essential fact is that in the castor oil 
seed two sorts of food are stored : one non-nitrogenous, in the 



SEEDS. y 

form of fatty oil; the other nitrogenous, in the form of aleurone. 
We shall find the same association of nitrogenous and non-nitrog- 
enous food substances in other seeds. 

IX. Prepare sections of the endosperm of a flax seed, 
and, as before, examine some in glycerine and others in 
water. How do the aleurone grains compare in size, form, 
and structure with those of the castor oil seed? 1 

X. Make a transverse section of a grain of wheat that 
has lain in water a few hours, cutting it in such a way that 
the section will show the coats of the grain and a portion 
of the endosperm. Mount in water. Notice 

1. The large cells making up most of the endosperm. 

What do they contain? 

2. Outside of these a layer of cells, rectangular in sec- 

tion, containing aleurone. 

3. The behavior of the substances contained in the 

different cells when iodine is applied. Draw a 
portion of the section. 

4. The arrangements for protection of the embryo, 

together with its food supply, by means of the 
united fruit and seed-coats. [The former consists 
of several layers of cells with strongly thickened 
walls, the latter of two very thin layers imme- 
diately outside the cells that contain aleurone. 
Tangential sections treated with sulphuric acid, 
compared with the transverse sections, will make 
the structure plain.] 

XT. Record in full what you have ascertained regarding 
reserve materials and their storage in seeds. What are 
the different kinds of non-nitrogenous food substances thus 

1 Cf. Erank, Lehrbuch der Pflanzenphysiologie, p. 158. 



10 STUDY OF COMMON PLANTS. 

far met with ? How are they recognized ? Mention cases 
where yon have found them associated with aleurone. 1 

Protection. 

I. Examine an orange with reference to the protection 
of the embryos. Make a transverse section of the fruit, 
and note carefully all the protective arrangements. 

II. Study an apple in the same way. 

III. Compare a number of commercial "nuts"; e.g. 
almond, chestnut, peanut, hickory nut, Brazil nut. Which 
are the most effectually protected ? How do they compare 
with other fruits in this respect ? 

IV. Make a transverse section of a grain of Indian corn 
and examine the pericarp microscopically. Notice the 
multiplication of thick-walled cells and their arrangement. 
Draw. 

V. After observing as many other seeds as are obtain- 
able, summarize your observations of the w T ays in which 
the embryo is protected against mechanical injuries, wet- 
ting, destruction by animals, attacks of fungi, etc. Are 
any that you have examined poorly protected ? 2 

Dispersal. 

I. Examine the seeds of common milkweed, Asclepias 
Cornuti, Decaisne. Compare those of the trumpet creeper, 
Tecoma radicans, Juss. Make an outline sketch of both. 

II. Study as many as can be obtained of the following : 
Seeds of willow or poplar ; fruits of elm, birch, maple, 
ash, clematis, hop tree, Ptelea, iron-wood, Ostrya or Carpi- 

1 Cf. Sachs, Physiology of Plants, pp. 323-340. 

2 Cf. De Candolle, Origin of Cultivated Plants, p. 395. 



SEEDS. . 11 

nut, thistle, dandelion, wild lettuce, cotton grass, Erio- 
phorum. 

In the air of a still room see whether any of these fall 
perpendicularly from a height of a few feet. What is the 
case when the air is disturbed by fanning ? 

III. Examine the fruits belonging to some or all of the 
following genera : Agrimonia, Geum, Desmoclium, Circaea, 
Galium, Lappa, Xanthium, Echinospermum, Cynogiossum, 
Bidens, Cenchrus. 

Describe the various appendages and compare them as 
to their efficiency. 

By means of a thread suspend weights to one of the 
hooked appendages of the , burdock and ascertain how 
great a weight the hook will bear. 

IV. Write out a list of fruits attractive to animals, 
taking care to include only such as you have yourself 
observed. 

V. Discuss any other arrangements for dispersal of seeds 
with which you are familiar. Read one or more of the 
references given below. 1 

RELATIONSHIPS INDICATED BY SEEDS. 

I. Examine seeds of mustard, radish, cabbage, and 
other cruciferous plants, comparing them with reference 
to their form and size, form and position of the embryo, 
nature of reserve material, and other points of difference 
and resemblance. The study will be facilitated by com- 
paring seeds that have been planted two or three days. 

1 Darwin, Origin of Species, Chap. XII; Lyell, Principles of Geology, 
Vol. II, Chap. XL; Hill, Am. Nat., 1883, pp. 811, 1028; Hildebrand, 
Verbreitungsmittel der PJlanzen ; Wallace, Darwinism. 



12 STUDY OF COMMON PLANTS. 

Draw and describe the various parts of some of the 
different seeds. 

II. Compare in the same way peas, beans, lima bean, 
lupine, and peanut. Are they essentially alike in struct- 
ure? Mention points of difference. 

III. Compare seeds of squash, pumpkin, watermelon, 
muskmelon, cucumber, and gourd. 

•IV. Compare seeds of tomato, egg plant, pepper, stra- 
monium, and hyoscyamus. 

V. Compare the seed-like fruits of sunflower, dandelion, 
thistle, lettuce, and salsify. 

In all the groups thus studied ascertain whether the 
seeds are more alike than different. Sections should be 
made and drawings introduced wherever they are needed 
to render the descriptions more intelligible. Some of the 
groups may be omitted if necessary, but the observations 
should be thorough and complete as far as they are 
carried. 

SPECIAL STUDIES. 1 

I. Polyembryony in the genus Citrus. This requires 

an extended comparison of seeds of different 

varieties of orange, lemon, and other citrus fruits. 

II. Arillate seeds. A study of the seeds of Celastrus 

scandens and other arillate species. 
III. Relation of the embryo to the reserve material. 
Arrangements that favor a prompt supply of food 

1 A few subjects for special study are given in connection with this 
and other exercises simply as examples of many that will naturally 
suggest themselves. In most cases the studies suggested require inde- 
pendent investigation, while others, such for example as number IV, give 
opportunity for reading and reporting on papers of special interest, par- 
ticularly those in recent periodical literature. 



SEEDS. 13 

to the embryo in early stages of germination. 
Cf. Haberlandt, Physiologische Pflanzenanatomie, 
p. 288 et seq. 
IV. Peculiar cases of plant dissemination. Cf. Ber- 
thoucl, Botanical Gazette, XVII (1892), p. 321. 
V. Identification of species by means of seeds. An 
interesting application will be found in the deter- 
mination of weed seeds of frequent occurrence in 
grass and clover seed. Cf . Beal, Grrasses of North 
America, I, p. 215. 

REVIEW AND SUMMARY. 

The seeds we have studied have been selected from 
three great classes of plants. To the first class belong 
the bean, castor oil, and other plants, the seeds of which 
have two cotyledons ; to the second, wheat, Indian corn, 
and, in general, all plants with one cotyledon ; and to the 
third, pines and their allies, many of which have more 
than two cotyledons. The distinctions between these 
classes are in many respects fundamental, so that an 
examination of the seed of a given plant is generally suffi- 
cient to enable us to determine its class in the vegetable 
kingdom. 1 

Furthermore, we have found that there are more re- 
stricted groups of plants, called families, the seeds of 
which are in many cases, though not in all, so nearly 
identical in structure as to indicate at once their family 
relationship. The squash, melon, and cucumber belong 
to one of these families ; the tomato, egg plant, and stra- 
monium to another, and so on. We conclude, therefore, 

1 Seedless or " cryptogamic " plants will be studied later. What is 
said in the present chapter and those immediately following applies to 
the higher or seed-bearing plants, including Gymnosperms. 



14 STUDY OF COMMON PLANTS. 

that the structure of seeds is an important factor in the 
determination of relationship. 1 

This being the case, it becomes necessary to formulate 
certain general conceptions of form and structure, and to 
Morphology adopt descriptive language by which they may 
of seeds. | )e expressed with clearness. 2 

The essential parts of a seed are the protective coats 
and the embryo with its store of food. The seed-coats 
commonly show a division into an external, 
hard, often colored, layer, the testa, and an in- 
ternal, more delicate one, the endopleura ; the former 
term, however, is frequently employed to designate the 
coats collectively. In many species the endopleura is 
wanting. Externally the testa may be smooth and pol- 
ished, as is the case with the seed of the castor oil plant, 
or it may be covered with hairs, as cotton seeds are, or, 
again, it may be extended into a wing, like that belong- 
ing to the seeds of the catalpa, and various other modifi- 
cations may occur, having, as a rule, a direct relation to 
protection or dissemination. An additional coat, usually 
colored and fleshy, known as the aril, is rarely present. 

The parts of the embryo are the radicle, cotyledons, and 
plumule. As we have seen, it may have one, two, or sev- 
eral cotyledons, and accordingly is said to be 
monocot3dedonous, dicotyledonous, or polycotv- 
ledonous. The embryo varies greatly in different species 
as regards form, position, and size, being straight or 
curved ; occupying the whole space within the seed-coats, 
or only a small portion of it; the cotyledons alike or dif- 

1 See, for example, "Rowlee, Bulletin of the Torrey Botanical Club, 
XX (1893), p. 1, and Rolfs, Botanical Gazette, XVII (1802), p. 33. 

2 For a more extended treatment of the morphology of seeds cf . Gray, 
Structural Botany. 



SEEDS. 15 

fering in size or shape, and so on ; l but these peculiarities 
are generally constant and characteristic in the species, or 
group of species, in which they occur. Whatever the 
form and position of the embryo, the radicle points towards 
the micropyle. 

Food materials of various kinds are stored up for the 
use of the plantlet during germination. If the tissue con- 
taining such reserve materials surrounds the 
embryo, it is called the endosperm, or, using an 
old phraseology, the seed is said to be albuminous. If, on 
the contrary, the reserve materials are stored within the 
embryo itself, even if they are of precisely the same 
nature, the seed is said to be without endosperm, or exal- 
buminous. 2 The terms are not well chosen, but have be- 
come so fixed as to render it necessary to recognize them. 

Certain structural peculiarities are intimately connected 
with the developmental history of seeds. They are at- 
tached to the mother plant by a minute stalk „„ 

, i t • i • • • i t Hlllim > raphe, 

through which nutritive materials are conveyed chalaza, mi- 
during their period of growth, but from which cr( W le ' 
they break away at maturity, leaving a scar called the 
hilum, such as is plainly seen on the common bean. From 
the hilum, in the great majority of cases, extends a fine, 
fibrous bundle, the raphe, like that of the castor oil seed, 
either the entire length of the seed, or for a shorter dis- 
tance, ending in a point, the so-called chalaza, where the 
seed coats cohere with each other and with the parts 
within. The raphe is simply a continuation of the stalk 
through which food materials were carried to the develop- 
ing seed, the chalaza being the point where the materials 

1 Cf. Lubbock, Seedlings. 

2 For the rare cases in which a distinction must be made between 
endosperm and perisperm, see Gray, Structural Botany, p. 310. 



16 STUDY OF COMMON PLANTS. 

were distributed to the interior of the seed. The hilum is 
in almost all cases a conspicuous feature, readily seen by 
the unaided eye, or with the help of a lens. The chalaza 
and raphe, on the contrary, are frequently obscured by 
the growth of the seed-coats. The micropyle is the open- 
ing between the seed-coats, readily seen in early stages of 
development, but often not easily recognized from the out- 
side of the mature seed. Its position is most readily 
determined by opening the seed and finding the radicle, 
which, as already said, points toward the micropyle. 

The form of the seed is also determined largely by the 

direction of growth of the ovule. In the majority of 

cases, of which the castor oil seed is a good 

Form as de- 1 j_i i i • i i -i 

terminedby example, the developing ovule turns upon its 
direction of longitudinal axis in such a way as to take an 
inverted position, so that in the mature seed 
the hilum and micropyle are close together, the chalaza at 
the opposite end, and the raphe running the whole length 
of the seed. Such seeds are said to be anatropous. 
Others, as, for example, the seeds of stramonium, are 
simply much curved, bringing both chalaza and micropyle 
near the hilum, one on either side of it. This is the 
so-called campylotropous form. In comparatively few 
species, of which buckwheat is an example, the axis of 
the ovule remains straight throughout its development, 
and the seed is said to be orthotropous. Modifications, 
particularly of the first and second forms, are of frequent 
occurrence. Cf. Gray, Structural Botany, pp. 278, 279. 

Physiologically, seeds present many points of interest- 
The arrangements for dispersal, for protection, and for 
Ph iolop-ical the support of the embryo in germination are 
adaptations, among the most important. 

A species generally has a better chance of survival if 



SEEDS. * 17 

the seeds are conveyed to some distance from the plant on 
which they are produced. By this means they 
are less likely to come into as close competition ls pe*&a . 

with each other as if they grew up together around the 
parent plant; they are also brought into other conditions 
of soil and surroundings, and the chances for cross-fertil- 
ization are greater, which, as we shall see, is often a 
marked advantage. Accordingly it is found that a variety 
of structures exist that are directly adapted to the dis- 
semination of seeds. Thus many seeds are distributed 
bj^ the action of the wind. These are most frequently 
light in weight and provided with appendages in the form 
of wings or hairs, such as those of the catalpa, poplar, 
milkweed, and many others. Seeds distributed by animals 
are often concealed within brightly colored or otherwise 
attractive fruits ; in other cases they are provided with 
hooks or other appendages by which they become attached 
to the wool or hair of various animals, and the seeds of 
many water-loving plants are carried in the mud that 
adheres to the feet of aquatic birds. The seeds of still 
others are w r ashed by oceanic currents to the shores of 
distant islands or continents, and, finally, the agency 
of man, both intentional and unintentional, becomes a 
potent factor in the distribution of plants. 

By these and other agencies the forms that constitute the 
vegetation of the earth have come to occupy the places in 
which we now find them, and it becomes for every species 
that we meet a fascinating and often intricate problem to 
endeavor to ascertain how it came to be where it is. 

It is plain that from the time they leave the mother plant 
to the time of germination, seeds are exposed 
to numerous dangers, and that they require pro- roteGt1011 ' 
tection. This is afforded in part by the shape of the seed, 



18 STUDY 6f common plants. 

most frequently a combination of strong arches, by which 
the danger of crushing is lessened ; in part by the hard 
testa, which sometimes has a compact, polished exterior 
that resists the entrance of water and germs ; and in some 
cases by bitter or otherwise distasteful substances stored 
up in the seed. In addition to these means of protection 
the embryo is often securely packed in the midst of 
abundant endosperm, and not infrequently still other pro- 
vision is made for its safety. 

Microscopic examination of a seed shows the presence 
of one or more kinds of reserve materials. As a rule. 
Reserve starch, or some other non-nitrogeneous sub- 

materials, stance, is associated with aleurone or its equiva- 
lent, thus supplying all the essential food elements. Oil, 
as a condensed form of food, is largely employed in small 
seeds and those that are transported by the wind, since by 
the use of this material greater lightness, volume for 
volume, is secured than if starch were employed. Cellu- 
lose takes the place of starch or oil in the date and some 
other seeds, which, as Haberlandt has pointed out, are in 
this way rendered less liable to decay and the attacks of 
animals during their long period of germination. 1 It is 
also seen upon the careful study of almost any seed that 
the reserve materials are so placed as to be ready for 
immediate use when wanted, either lying in the cells of 
the embryo itself or packed closely around it, and there 
brought into immediate relation with its absorbing tissue. 

Still other physiological adaptations will be apparent as 
a greater number of seeds are examined and their struct- 
Other adapta- ura l peculiarities brought to light. As an exam- 
tions. pi e ma y t^ mentioned the fact that anatropous 

seeds by curving upon themselves during the early stages 
1 Physiologische Pflanzenanatomie, p. 285 et seq. 



SEEDS. 19 

of their development bring the micropyle into such a 
position as to favor trie entrance of the pollen tube. 
Again, the hairy appendages of numerous achenia, such 
as those of the dandelion and related plants, are so placed 
as to bring the radicle on the lower side as the object 
alights on the surface of the ground. 1 Such adaptations 
are of so constant occurrence that the student can hardly 
fail to receive the impression, in general a correct one, 
that the simplest structural facts are likely to have some 
important physiological significance. On the other hand, 
there are numerous cases of " accidental " peculiarities, for 
which no reason is manifest, and which at present are not 
explained. 

1 Cf. Rowlee, I.e. 



20 STUDY OF COMMON PLANTS. 



II. GROWTH OF PLANTS FROM THE SEED. 

MATERIAL REQUIRED. 

Seedlings of the common bean, pea, sunflower, white mustard, flax, 

and hemp, from one to four weeks old. 1 
Seedlings of Indian corn and wheat of various ages. 
Pine seedlings from a few weeks to a few months old. 
Seeds of squash and other cucurbits in early stages of germination. 

I. Take seedlings of different ages of the plants named 
in the first list above. Wash the roots and let them stand 
in a dish of water to prevent drying. Compare them and 
satisfy yourself as to the following points : 

1. Do they all have a taproot? 

2. Do they all have a hypocotyl, i.e. a stem supporting 

the cotyledons ? 

3. How do the cotyledons of the different plants differ 

a. As to form and size? 

b. In function ? Have any of them wholly lost their 

function as foliage leaves? Are there any 
apparently transitional forms, as if this function 
were partially lost ? 

4. How does the pea differ from the sunflower in the 

time of unfolding the proper foliage leaves ? Can 

1 The seeds should be sown at intervals of a few days, some in sand, 
others in moist (not wet) sawdust, and still others on folds of damp 
blotting paper under a bell- jar. There should be three or four lots of as 
many different ages. Pine seedlings, which are rather difficult to raise, 
may be obtained from nurseries. 



GROWTH OF PLANTS FROM THE SEED. 21 

you suggest any reason for this difference? How 
do the other seedlings compare in this respect? 

II. Compare the seedlings of Indian corn and wheat 
that have attained the height of several inches. 

1. Describe the cotyledon. Has it undergone any 

change during the process of germination ? x 

2. Is there a taproot? 

3. Mention all the points -in which the two plants are 

alike ; those in which they differ. 

III. Compare the seedlings of the Indian corn and 
wheat with those of the pea, bean, etc., previously studied. 
Point out all the essential differences, noting especially 

1. Number of cotyledons. 

2. Venation of foliage leaves. 

3. Position and form of leaves. 

4. Presence or absence of a persistent taproot. 

IV. Examine seedlings of the white pine or other species 
of pine. In what important feature do they differ from 
any of the young plants thus far studied ? 

V. Summarize your observations and show how the 
class to which a plant belongs may be determined by 
inspection of the seedling. 2 

VI. Comparing the seedlings of different dicotyledonous 
plants (beans, sunflower, etc.), ascertain whether any of 
them have the two cotyledons unlike in size or shape. Is 
there anything to indicate that the form of the embryo 
is determined by that of the seed ? 3 

1 The protective sheath is regarded as a part of the cotyledon, while 
the other part, the scutellum, remains in the grain. Cf . Lubbock, Seed- 
lings, II, p. 587. 

2 Cf . Gray, Structural Botany, Chap. II. 

3 Lubbock, Seedlings, I, pp. 30-34, 75-77. 



22 STUDY OF COMMON PLANTS. 

VII. Notice the way the different seedlings break 
through the ground. Do those of all the dicotyledonous 
plants behave alike ? How do they compare with those 
of Indian corn and other monocotyledons ? x 

VIII. Examine seedlings of squash, melon, or cucum- 
ber, comparing specimens that are just rupturing the testa 
with older ones. Observe the position and structure of 
the "peg," and the way it aids in throwing off the seed- 
coats. 2 

IX. Ascertain whether direction of growth is affected 
by external conditions. 

1. Compare mustard or other seedlings grown in the 

dark with others growing in front of a window. 

2. Turn on their sides some of the pots with seedlings 

a few inches high, and after a day or two notice the 
result. 

3. Observe the effect of slow change of position in neu- 

tralizing geotropism and heliotropism. 3 

X. Take up a seedling of wheat about two weeks old, 
and examine the grain. 

1. Notice how it differs from a grain that has not 

sprouted. 

2. Remove a small portion of the endosperm and ex- 

amine under a high power of the microscope. 
Compare the starch grains with those of wheat 
that has not sprouted. What changes have taken 
place ? Draw some of the grains that show " cor- 
rosion." 

1 Darwin, Power of Movement in Plants, p. 77 et seq. 

2 Darwin, I.e., p. 102. 

3 For this purpose an instrument known as a klinostat is employed. 
Cf. Goodale, Physiological Botany, p. 408; Sachs, Physiology of Plants, 
p. 684. Less expensive apparatus is easily devised. 



GROWTH OF PLANTS FROM THE SEED. 23 

3. Examine in the same way starch from the endosperm 
of a corn seedling that has attained several inches 
iii height. 

o 

XL Write a detailed account of the phenomena of 
germination as far as you have observed them. 

SPECIAL STUDIES. 

I. How seedlino-s break through the ground. A 

further comparison, including the study of as 
many species as practicable. 

II. Results of planting certain seeds wrong side up. 1 

III. Results of removal of cotyledons at an early stage 

of growth. 

IV. Whether detached embryos are capable of germi- 

nation. 

V. Conditions most favorable to germination. 

VI. Length of time that seeds retain their vitality. 

VII. How far seedlings of the same family are alike in 
structure and habits. 

VIII. Changes capable of demonstration under the micro- 
scope that take place in reserve materials during 
germination. 

REVIEW AND SUMMARY. 

In our study of seedlings we have found that the same 
parts are present that were observed in the seed, but 
marked changes have taken place in size, position, texture, 
and other particulars. The distinctive features of the 

1 Cf. Darwin, I.e., pp. 103, 104. 



24 STUDY OF COMMON PLANTS. 

great classes, however, are as strongly marked as they 
were in the seed, and each class exhibits in its seedlings 
characteristic, though not always distinctive, habits. 

The radicle of dicotyledonous seedlings elongates and 
extends downwards as the primary root, and at the same 
time in most species grows upward, forming the 
nous seed- " hypocotyl," at the upper extremity of which 
lmgs ' the cotyledons are borne. In some species, as 

in the pea, the hypocotyl is wanting, or is extremely short, 
the cotyledons remaining in the ground instead of being 
lifted into the air. In such cases a rapid development of 
the "epicotyl," or first internode of the plumule, takes 
place, thus securing to the young leaves ^s they unfold 
full exposure to air and light. The hypocotyl (or, if this 
is wanting, the epicotyl) breaks through the ground in the 
form of an arch, an arrangement for the protection of the 
delicate growing point. 1 

Monocotyledonous seedlings exhibit considerable variety 

among themselves, although several pretty distinct types 

, , may be recognized. In the grasses the scutel- 

Monocotyledo- . 

nous seed- lum, which represents a part of the cotyledon, 
lings. remains enclosed in the grain, and the straight 

plumule is erect, instead of arched, as it breaks through 
the ground. In many other species, as for example the 
date palm, a peculiar modification of this mode of germi- 
nation is seen. As before, a part of the cotyledon remains 
in the seed as an organ of absorption, but the other end 
elongates and grows downward, forming a sheath from 
which the first leaf afterward emerges. 2 A more or less 
conspicuous primary root may be present, as in Indian 

1 Cf. Darwin, Power of Movement in Plants, pp. 87, 88. 

2 See figures of palm seedling, Goebel, Classification and Special Mor- 
phology of Plants, p. 432. 



GROWTH OF PLANTS FROM THE SEED. 25 

corn, or it may be hardly distinguishable from the secon- 
dary roots, as is the case with wheat. 

Seedlings of pines and their allies (gymnosperms), aside 
from the fact that many species have more than two coty- 
ledons, can hardly be said to possess characters seedlings of 
specially distinctive of their class. In many gymnosperms, 
cases the testa is carried up on the tips of the cotyledons, 
and afterwards thrown oil by their bulging outwards. In 
some species the cotyledons remain under ground. 

Cotyledons, as a rule, perform functions widely different 
from those of ordinary green leaves, and accordingly pre- 
sent striking modifications of form and structure. „ ^_. a 

° Cotyledons 

While in some cases they unfold and deport and their mod- 
themselves as foliage leaves, in others, as for i^ 10118, 
example the pea and acorn, they have lost nearly all 
resemblance to leaves, and serve merely as storehouses of 
reserve materials ; while in still other cases, as in the grain 
of corn or wheat, the cotyledon becomes largely an organ 
of absorption. Interesting transitional forms are seen in 
the common bean and other plants in which the cotyle- 
dons rise above the surface and turn green, but soon dry 
up after their reserve materials are exhausted. The 
embryos of some dicotyledonous plants produce but one 
cotyledon, the other being rudimentary. A curious in- 
stance is that of the orange, in the seed of which several 
embryos are formed with cotyledons varying greatly in 
size. In various species of cacti both cotyledons are rudi- 
mentary, being represented by minute bodies only a milli- 
meter or two in diameter. In the latter case the radicle is 
thickened and serves as a storehouse, the cotyledons be- 
come superfluous, and are finally reduced to insignificant 
appendages, an illustration " of the principle of compensa- 
tion or balancement of growth, or, as Goethe expresses it, 



26 STUDY OF COMMON PLANTS. 

1 in order to spend on one side, Nature is forced to econo- 
mize on the other side.' " 1 A considerable number of 
seeds, notably those of certain plants belonging to the 
mustard family, have one cotyledon larger than the other, 
an arrangement naturally following the way the embryo 
is packed in the seed. These and various other peculiar- 
ities may be seen in the embryo before germination, but 
are more pronounced in the young seedling. 

During germination the reserve materials stored in or 
around the embryo are drawn upon for the sustenance 
n , of the seedling 1 . Microscopic examination of 

Changes o r 

in reserve the endosperm of a grain of wheat or Indian 
corn, after the seedling is well started, shows 
that the starch granules have undergone remarkable 
changes due to the action of a ferment that gradually 
dissolves them. Other reserve materials, such as oil, 
aleurone, etc., undergo similar changes, by which they 
are fitted for absorption, but these are too complicated 
to be discussed in an elementary work. Those interested 
in the chemistry of germination should consult Sachs, 
Physiology of Plants, and later articles in various botan- 
ical periodicals. 

Certain external conditions are essential to germination. 
Of these the most important are (1) a suitable amount of 
Conditions of water, (2) proper temperature, and (3) access 
germination. f oxygen. Simple experiments are easily con- 
ducted to establish these facts, which are also, in part, 
matters of familiar observation. Thus when a crop of 
grain has been sown it is well understood that it will not 
come up if the earth is too dry, and that it is more likely 
to decay in the ground than to germinate if it is too wet, 

1 Cf. Darwin, Poiver of Movement in Plants, pp. 94, 98 ; Lubbock, 
Seedlings, II, p. 6. 



GROWTH OF PLANTS FROM THE SEED. 27 

and careful experiments go to show that seeds sprout 
more promptly and surely with a less amount of water 
than is commonly supplied in artificial cultures. Too 
high or too low a temperature is equally unfavorable, 
although there is a pretty wide range within which most 
seeds will germinate. An even temperature is found to 
be more favorable to prompt germination than a variable 
one. Finally, if oxygen is excluded, even if all other con- 
ditions are fulfilled, germination fails to take place. It is 
for the purpose of securing an abundant supply of oxygen 
that we leave the sawdust lying up loosely, rather than 
closely packed, about the seeds, when we are raising seed- 
lings in the laboratory. For the same reason, a light, 
loose soil is more favorable for gardening than a compact 
and heavy one. These conditions are well known, and 
are taken into account in practical operations, although a 
comparison of different seeds during germination estab- 
lishes the equally important fact that both individual and 
specific peculiarities exist. Some seeds require more 
moisture than others, and the degree of temperature most 
suitable for germination varies with different species, and 
so on. An interesting series of experiments on the condi- 
tions of germination and the individual peculiarities just 
referred to has been carried out at the Cornell University 
Experiment Station. For an account of these, see Science, 
XIV (1889), p. 88. 

Some of the phenomena connected with germination are 
of much interest and are easily observed. The first step 
consists in the forcible absorption of water, ^ tten( j ant p h e _ 
manifested by the great increase in size of ger- nomena. 
minating seeds, and the pressure they exert if an attempt 
is made to confine them in a closed vessel. Testing with 
a thermometer shows that the process of germination is 



28 STUDY OF COMMON PLANTS. 

accompanied by a rise of temperature, and chemical ex- 
amination indicates absorption of oxygen and exhalation 
of carbon dioxide; in other words, respiration is going on. 
The length of time during which seeds retain their 
vitality has been the subject of much discussion. Stories, 
Duration of frequently repeated, of the growth of grain 
vitality. many centuries old, taken from Egyptian tombs, 

and of raspberry seeds from a Roman skeleton in England, 
etc., are generally discredited, for the reason that sufficient 
proof is lacking. On the other hand, a series of experi- 
ments, conducted for a long period by a committee of 
the British Association for the advancement of science, 
shows that some seeds have certainly retained their ca- 
pacity for germination from twenty to forty years, and 
even longer. 1 

1 Report of British Association, 1857, Dublin meeting. 



THE ROOT. 29 



III. THE ROOT. 

MATERIAL REQUIRED. 

Roots of Indian corn and other seedlings used in the preceding 
exercise. 

The lower parts of a fully grown corn-stalk, showing the supporting- 
roots. 

Aerial roots of English ivy, or trumpet-creeper. 

Turnips and other fleshy roots from the market. 

Slips of Verbena, Tradescantia, and other common conservatory 
plants. 

I. Examine more in detail the roots of seedlings already 
studied. 

1. Taking specimens of Indian corn of different ages, 

note 

a. Where the secondary roots arise. 

b. Whether any of them have given rise to roots of a 

higher order. 

c. How they compare in these particulars with those 

of wheat. 

2. Compare the roots of the sunflower, bean, and pea 

with reference to the same points. 

II. Study the root-hairs of various seedlings, beginning 
with some that are growing on blotting paper. 

1. On w^hat parts of the roots are they produced ? 

2. Remove, with a pair of fine forceps, a portion of a 

root where it is thickly covered with root-hairs. 



80 STUDY OF COMMON PLANTS. 

(The roots of wheat or oat seedlings are excellent 
for this purpose.) Mount in water, taking care 
not to injure the delicate tissue by undue press- 
ure. Examine under a high power of the com- 
pound microscope. 

a. Observe the structure of the root-hairs. 

b. Ascertain how they are connected with the body 

of the root. Draw. 

c. Run iodine solution under the cover glass, and 

watch the effect. # What do you infer as to the 

permeability of the cell membrane and the 

capacity of the cell contents for absorption ? 

3. Pull up a specimen that has grown in clean sand. 

Shake off as many of the adherent particles as 

possible. Examine under a good lens. It will be 

seen that many grains of sand still remain attached. 

Ascertain whether this is due in any way to the 

presence of root-hairs. 

III. Cut off the tips of some of the fine roots of wheat 
or oats grown under a bell-jar. Mount in water, and 
examine with the compound microscope. Select a good 
specimen, and draw the end carefully so as to show the 
root-cap. 

IV. Determine in what part of the root increase in 
length takes place. Use for this purpose roots of Indian 
corn, peas, or sunflower, growing on moist blotting paper 
under a bell-jar. With a camel's-hair brush and india ink 
make a series of marks at intervals of a millimeter, begin- 
ning at the apex of the root. Replace the bell-jar, and as- 
certain by subsequent observations, about a day apart, 
where elongation has taken place. 

V. Determine the direction naturallv taken bv roots. 



THE ROOT. 31 

1. Pull up beans or peas that have been growing in saw- 

dust, and observe the entire root system. How 
do the secondary roots compare with the primary 
in their direction of growth? If roots of a higher 
order have been formed, ascertain whether they 
take the same direction as either of the preceding. 
Would it be advantageous for the plant if all grew 
downward ? 

2. Take a germinating pea or squash seed, with a radi- 

cle a centimeter or more in length, and fasten it 
to a cork by a pin so that the radicle will point 
horizontally. Keep it in a moist atmosphere under 
a bell-jar, and exclude the light by covering with 
a dark cloth. Observe the subsequent growth of 
the radicle. Vary the experiment by turning 
other specimens so that the radicle will point 
nearly vertically. 

3. Tie a piece of netting over the mouth of a beaker or 

wide-mouthed bottle filled with water, and place on 
it a number of seeds of white mustard that have 
just begun to germinate. Allow the apparatus 
to stand in front of a window without being dis- 
turbed, filling with water occasionally, so that the 
growth of the seedlings will be uninterrupted. 
' Observe the direction taken by the roots. 

VI. Examine different roots with reference to their 
mechanical functions. 

1. The supporting roots of Indian corn. Notice where 

they originate, their direction of growth, and their 
double action as braces and guys. 

2. Aerial roots of the English ivy, or trumpet-creeper. 

Compare these with ordinary roots. 



32 STUDY OF COMMON PLANTS. 

3. Examine under a lens the structure of a blackberry 
root, or that of some other common woody plant. 
Cut a transverse section, and notice the position 
of the wood elements. Compare this with their 
arrangement in the stem. A little reflection will 
show that the arrangement of the mechanical ele- 
ments corresponds with the very different condi- 
tions that obtain in root and stem. The former 
must be so constructed as to resist a force that 
tends to pull it out of the ground ; in the latter, 
on the other hand, resistance to a lateral and ver- 
tical force must be provided for. 1 
Other roots should be examined in the same way. 
Those of Indian corn seedlings will be found 
useful. 

VII. Compare fully grown turnips and carrots, radish, 
or salsify with the roots of seedlings of the same plants. 
What changes of form and structure have they undergone ? 

VIII. Study the formation of adventitious roots, as 
seen in Verbena and other plants, grown by florists from 
slips. Adventitious roots of Tradescantia can be obtained 
by placing a fresh branch in a closed bottle so that the 
cut end will stand in a little water at the bottom. 

SPECIAL STUDIES. 

I. Protection of the growing point of the root. A 
number of water plants furnish excellent material 
for microscopic study of the root-cap. Among 
them are Lemna minor, common everywhere in 
stagnant waters, and Pontederia crassipes, fre- 
quently grown in artificial ponds. Certain aerial 

1 Cf. Haberlandt, Physiologische Pflanzenanatomie, p. 125 et seq. 



THE ROOT. 33 

roots, as those of Pandanus, commonly culti- 
vated in conservatories, also have remarkably 
developed root-caps. 

II. Conditions affecting the formation of root-hairs. 
An interesting investigation is suggested by 
Haberlandt, Physiologische Pflcmzenanatomie, p. 
147 et seq. 

III. Propagation of plants by slips and cuttings. Ascer- 

tain what plants are regularly propagated in this 
way by florists and what conditions are necessary. 

IV. Reserve materials stored in roots. Examination of 

the blackberry, elecampane, and other roots, to 
determine the nature of the food substances con- 
tained in them. 

V. Influence of moisture on the direction taken by 
roots. " Search for water " by roots of trees. 

VI. Minute anatomy of roots. (This may be deferred 
with advantage until the stem is studied micro- 
scopically.) 

VII. Estimate of the total length of the root system of 
some common plants. Johnson, How Crops 
Grow, p. 242. 

VIII. Roots of parasites. Sections of roots of Comandra 
or mistletoe, with a study of their relation to the 
plants on which they have fastened. 

REVIEW AND SUMMARY. 

Roots function as organs of absorption, as storehouses of 
reserve materials, and as a mechanical means of holding 
the plant firmly in its place. 



34 STUDY OF COMMON PLANTS. 

As organs of absorption, it is essential that they should 
have a large extent of surface in contact with the soil. 
Roots as ^ n P ^ 11 ^ U P seedlings of different sorts it is 

organs of apparent that the total length of their roots 
a sorp ion, ^ g ma ny times that of the aerial parts, and this 
is frequently still more striking when the earth is carefully 
washed away so as to expose the whole root system of 
older plants. The surface is further increased by the 
formation of root-hairs. These are delicate, elongated 
cells, arising from the roots back of their growing point, 
and so numerous under favorable conditions as to give 
them a densely hairy appearance, easily noticeable to the 
unaided ej^e. By their adhesive surface the root-hairs 
attach themselves closely to the particles of soil, and by 
means of acid excretions aid in preparing for absorption 
the crude food materials of the earth. These substances, 
in solution, are then taken up and carried to the parts 
within. It is, moreover, through the agency of the root- 
hairs that the enormous volume of water evaporated by 
the leaves of plants in full foliage is taken up from the 
soil and started on its upward course. 1 

The roots of many plants, particularly those that live 
more than a year, fulfil an important function as reservoirs 
Roots as °f reserve materials upon which the plant draws 

storehouses, w hen it begins anew its period of active growth. 
Suitable tests show that starch and sugar are the food 
substances most commonly stored in roots ; inulin also 
occurs, though more rarely. These and other vegetable 
products are described in detail by Sachs in his Physiology 
of Plants. The shape taken by roots that serve as store- 
houses is sometimes quite characteristic. As examples 

1 Johnson, How Crops Grow, p. 243 ; Haberlandt, Physiologische 
Pflanzenanatomie, pp. 148, 149. 



THE ROOT. 35 

may be mentioned, the napiform roots of most turnips, the 
conical roots of carrot, salsify, etc., the moniliform roots of 
some pelargoniums, and so on. 

Besides acting as organs of absorption and as storehouses 
of reserve materials, roots fulfil an important function in 
holding the plant firmly in its place. A study Mechanical 
of the arrangement of their tissues shows a functions. 
manifest adaptation to this function, the mechanical ele- 
ments being placed compactly at the center, a position in 
which they are able to resist to the best advantage a 
pulling force that tends to break the root or draw it out 
of the ground. Such aerial roots as those of the poison 
ivy serve to hold the stem securely to some external sup- 
port, and the prop roots of Indian corn that arise a little 
above the surface of the ground constitute an admirable 
system of braces and guys, by which the stalk, with its 
heavy load of ears, is enabled to maintain an erect posi- 
tion. Considering the size and weight attained by a 
single cornstalk with its fruit, and its exposure to heavy 
winds and rain, it is difficult to conceive of a more 
effective and, at the same time, more simple mechanical 
arrangement. 

In their mode of growth roots exhibit a remarkable 
adaptation to their environment. Growth in length takes 
place just behind the tip, which is thus free to Mode of 
turn in any direction, curving aside as it meets growth. 
obstacles, and directing its way towards moisture or food, 
as occasion requires, without involving any disturbance of 
the older parts that have already become fixed in the soil. 
The growing point is covered by the root-cap, and thus 
protected from injury. 

The primary root groivs perpendicularly downwards, 
but the secondary roots, reacting differently to the pull of 



36 STUDY OF COMMON PLANTS. 

gravitation, grow down obliquely, while roots of a higher 

order extend indifferently in various directions. The 

. result is such a distribution of the root system 

Primary and ... . . 

secondary as to bring it into contact with the soil far more 
perfectly than if the roots grew down together 
in a common bundle. It has been noticed, however, that if 
the end of the primary root is destroyed one or more of the 
secondary roots near it grow vertically downward to take 
its place. 1 

While the branches arising from the first or primary 
root are properly called secondary, the same term is also 
Adventitions frequently applied to roots of a higher order, 
roots. and is sometimes rather loosely extended to 

those given off by the stem and other parts of the plant. 
The latter, however, are commonly spoken of as adventi- 
tious. Aerial roots, such as those of the ivy and trumpet- 
creeper, properly fall under this head. Other adventitious 
roots are of great importance in the practical operations 
of florists and gardeners, enabling them to increase their 
stock by taking advantage of the capacity of slips and 
cuttings for promptly forming roots. The readiness with 
which cuttings of willows and poplars produce adventitious 
roots, together with their rapid growth, has led to their 
extensive planting in the western states, and many trouble- 
some weeds owe their pertinacious hold on the soil to the 
same habit. 

In a comparatively small number of plants, of which the 
dodder is a familiar example, adventitious roots take the 
Parasitic form of suckers which penetrate the tissues of 
habits, other plants, on which the} r live as parasites. 

The plant thus attacked is called the host, from the rela- 
tion in which it stands to its parasite. But few flowering 

1 Darwin, Power of Movement in Plants, p. 196. 



THE KOOT. 37 

plants have become truly parasitic, the habit, as it occurs 
in the vegetable kingdom, being chiefly characteristic of 
fungi. 

In their microscopic structure roots exhibit essentially 
the same tissues and elements as are found in the stem, 
which we shall soon study in detail. There are, Minute anat- 
to be sure, certain differences of arrangement, om y' 
already mentioned in connection with the mechanical func- 
tion of roots, that cannot here be discussed at length. 
Those who wish to make a thorough study of the minute 
anatomy of roots will find the necessary assistance in such 
works as Strasburger's Practical Botany and De Bary's 
Comparative Anatomy of the Phanerogams and Ferns. 



38 STUDY OF COMMON PLANTS. 



IV. THE STEM. 

MATERIAL REQUIRED. 

Fresh shoots of apple-tree, grape-vine, oak, elder, and bass wood. 
Stalks of Indian corn put up in alcohol after they have attained full 

size. Stems of common greenbrier, Smllax rotund if olia, L. 
Shoots of white pine from one to three years old, preserved in alcohol. 

Similar specimens of arbor vitse or of red cedar. 
Specimens of white oak, hickory, ash, Norway spruce, palm, and other 

woods, showing transverse and longitudinal sections. 
A collection of greenhouse plants, including rose geranium, primrose, 

Coleus, Tradescantia, and others. 
Tendrils of grape-vine, spines of honey locust, common potato, and 

such other modified stems as are procurable. 

STRUCTURE AND MODE OF GROWTH. 

I. Study first the gross anatomy of a number of woody 
stems. 

1. With a sharp knife make a transverse section of a 

one-year-old shoot of an apple-tree. Examine 
under a good lens, and draw an enlarged outline, 
showing the position and relative proportions of 
pith, wood, and bark. 

2. Separate the bark into its three layers, 

a. External, corky layer. 

b. Middle, green layer, not sharply delimited from the 

c. Inner bark, or bast. 

Try the strength of these different parts by sepa- 
rating and pulling upon them. 



THE STEM. 39 

3. Examine the wood closely. Notice the medullary 

rays, appearing like lines radiating from the pith. 
Careful inspection shows numerous openings in 
the wood between the medullary rays. These are 
the ends of vessels that convey water and air 
through the stem. It can also be observed that 
the pith is made up of minute cells. These struct- 
ures may be seen still more readily in the grape- 
vine. 

4. With the stem of the apple-tree compare those of the 

grape-vine, common elder, and oak, making trans- 
verse sections, as before. In what respects do 
they all agree ? How do they differ? 

II. Examine the stem of Indian corn, making both 
transverse and longitudinal sections. What part of the 
stem has the firmest tissue ? 

Make an outline sketch of the transverse section, show- 
ing the position of the woody parts as they appear under 
a good lens. Compare with this a similar section of the 
stem of a palm or other monocotyledonous plant. Com- 
mon greenbrier is suitable for this purpose. 

III. Study shoots of white pine, two or three years old, 
that have lain some time in alcohol. Indicate by means 
of a diagram the relative position of pith, wood, and bark. 

Using an older, dry specimen, that has been cut so as 
to show a smooth transverse section, notice the succession 
of annual rings. How does the outer edge of each ring 
differ from the inner? Determine the age by counting 
the number of rings. Examine the stem of the arbor 
vitse or red cedar, and see if it corresponds in structure 
with that of the white pine. 

IV. Write an account of the different stems you have 



40 STUDY OF COMMON PLANTS. 

studied. Show how the stem of a monocotyledon, such as 
Indian corn, differs from that of the apple-tree and other 
dicotyledonous plants. With which do the stems of the 
conifers (pine, arbor vite, etc.) agree? 

V. Ascertain the age of specimens of white oak, hickory, 
ash, pine, and Norway spruce, by counting the annual 
rings. The work must be done with care, in order to 
insure accuracy. In examining large sections, draw a 
straight line from the center to the periphery, and mark 
off on it intervals of exactly one inch, beginning on the 
outside. Count the number of rings in each division and 
record them in their order. Compare the rapidity of 
growth of the pine and spruce ; of the ash and hickory. 1 

MINUTE ANATOMY. 

I. Take fresh shoots of the apple-tree, and cut a number 
of transverse sections. Mount some in water, others in 
glycerine, and still others in Schulze's solution for micro- 
scopic study. 2 Examine first with the low power. Tak- 
ing the parts in order, beginning with the outside, we find 

1. The outer bark, or cork, consisting of several layers 

of flattened cells with reddish-brown contents. 
(The remains of the epidermis outside of the cork 
may be disregarded.) 

2. The middle bark, or cortical parenchyma, consisting of 

a broad zone of cells with green contents (chloro- 
phyll). Near the inner edge of this zone are 
bundles of thick-walled elements, bast fibers. The 

1 Other species may of course be used if more convenient. 

2 The success of the work depends upon having good sections to study. 
Worthless ones must be thrown away, and sectioning continued until 
entirely satisfactory specimens are obtained. 



THE STEM. 41 

latter are nearly colorless, their very small cavity 
showing as a dark point at the center. 

3. The inner bark. This is best studied in stems four 

or five years old. It is composed of 

a. Sieve-tubes, narrow elements with light-colored 

walls. 

b. Bast parenchyma, much wider cells frequently con- 

taining chlorophyll. 

c. Bundles of bast fibers similar to those already 

described. 

4. Cambium. In the winter a sharp line of demarcation 

between wood and bark is seen, but in spring there 
is formed a zone of fresh tissue known as the cam- 
bium, from the inner cells of which a new layer of 
wood is produced, and from the outer ones a new 
layer of bark. See VII below. 

5. The wood. In this observe the following : 

a. Vessels with large openings. 

b. Wood fibers, smaller elements with narrow lumen 

and thick wall. 

c. Wood parenchyma. This is more easily made out 

on longitudinal section. 

d. Medullary rays, extending from the pith outwards 

and continuous with those of the inner bark. 

6. Pith, consisting of very large cells marked by numer- 

ous pits. 

II. Prepare next a number of radial longitudinal sec- 
tions, mounting as directed above, and study in the same 
order, comparing them, step by step, with corresponding 
parts of the transverse sections. 

1. Ascertain whether the cork cells present the same 
appearance on transverse and longitudinal sec- 



42 STUDY OF COMMON PLANTS. 

tions, and in the same way compare the cells of 
the cortical parenchyma as seen in both. 

2. Taking the inner bark next, the sieve-tubes are 

easily recognized by their narrowness and length, 
and also by their soft, light-colored walls, while 
the bast parenchyma consists of much shorter and 
wider cells. The medullary rays present a marked 
appearance, looking, on radial sections, like brick 
work. 

3. Look for crystals of calcic oxalate, often found in con- 

siderable numbers in cells adjacent to the sieve- 
tubes. 

4. The bast fibers are to be looked for in places corre- 

sponding to their position in the transverse section. 
They may or may not be found in some of the lon- 
gitudinal sections. Why ? 
When you have found them, note the points in which 
they differ from all the other elements of the bark. 

5. Passing to the wood, the large pitted vessels are at 

once recognized. It is seen that they are com- 
posed of long cylindrical cells placed end to end, 
their dividing walls having been absorbed, or with 
only traces of them remaining, so that they form 
continuous ducts. The wood fibers also are 
greatly elongated, but are much narrower. Their 
walls are very thick and the ends tapering, fitting 
to each other so as to make a very compact and 
solid tissue. 
Notice whether the medullary rays present the same 
appearance in the wood as in the bark. Test the 
contents with iodine solution. Cells resembling 
those of the medullary rays, but extending length- 
wise of the stem, will be found. These constitute 
the wood parenchjrma. 



THE STEM. 43 

6. The pith comes last, and presents no difficulties. 

7. Having compared the two sections throughout, go 

over them again and see if all is clearly under- 
stood. Make yourself familiar with all the details 
of structure. Note what cells contain chlorophyll, 
where starch occurs, the action of Schulze's solu- 
tion on different parts, whether the sieve-tubes 
show any peculiarities corresponding to their name, 
how the cork originates, the manifest resistance of 
the cork cells to reagents, and so on. Write a full 
account, and introduce drawings wherever they are 
required to make the description clear. 

8. Finally cut tangential longitudinal sections, and 

compare with the preceding. 

III. Stem of Indian corn. Cut thin transverse sections. 
Examine first with the low and afterwards with the high 
power. The following parts are seen: 

1. The epidermis and sub-epidermal tissue, forming a 

continuous peripheral zone of thick-walled cells. 

2. Fibro-vascular bundles, more numerous near the out- 

side of the stem. 

3. Fundamental tissue, consisting of large cells similar to 

those composing the pith of the apple-tree stem. 

IV. To understand these parts it will be necessary to 
compare them carefully with the same structures as seen 
in longitudinal section. Accordingly, with both trans- 
verse and longitudinal sections on the slide, study each 
part in detail. 

1. Observe the epidermis from both points of view. 

Draw a few cells. 

2. The fibro-vascular bundles present a somewhat com- 

plicated structure. They are bounded externally 



44 STUDY OF COMMON PLANTS. 

by strong bands of thick-walled cells, composing 
the so-called bundle-sheath, which may be continu- 
ous, or thinned out on the sides of the bundle. 
The bundle itself presents two parts for study : first, 
the xylem, or wood, which includes the two conspic- 
uous pitted vessels (recognized by their very large 
openings), and the parts immediately adjacent; 
and second, the phloem, or bast portion, marked 
by the peculiar appearance of its elements on 
transverse section, its small cells being fitted in at 
the angles between larger ones in such a way as 
to give the effect of mosaic work. 
Studying first the xylem, on both transverse and 

longitudinal sections, we find that it consists of 
a. The large pitted vessels already noticed. Ex- 
amine their structure carefully, observing par- 
ticularly the remains of the partition walls in 
the form of heavy rings, indicating the origin 
of the vessels in rows of cells placed end to 
end. One or more smaller vessels lie between 
them, and a little nearer the center of the 
stem. One of these is conspicuously marked 
by heavy thickenings in the form of rings, and 
is called an annular vessel. Frequently the 
surrounding tissue is absorbed, leaving only 
the rings of the annular vessel to mark its 
place. 
5. Thick-walled elements lying between the large 

pitted vessels. 
c. Elements with thinner walls surrounding the an- 
nular vessel. Some of these, as already stated, 
have disappeared, leaving an irregular open 
space. 



THE STEM. 45 

The two sorts of elements that compose the phloem 
are easily recognized on both transverse and 
longitudinal sections. 

a. The sieve-tubes are large, with nearly or quite 

transparent contents, and here and there a per- 
forated transverse septum looking like a sieve. 

b. The smaller cells placed at the angles of the 

sieve-tubes are the cambiform, or companion, 
cells. Their thicker contents, smaller diame- 
ter, and the absence of sieve-plates at once dis- 
tinguish them from the preceding. 
Having identified all the parts that have been 
named, study them closely, and after you have 
become perfectly familiar with the position and 
structure of the different elements, draw and de- 
scribe them. Meantime, look for any additional 
features to which your attention has not thus far 
been specially directed. See if you can recognize 
the protophloem, a small group of rather indistinct 
cells lying between the phloem and the bundle- 
sheath. 
Study, too, more carefully, the structure of the sieve- 
tubes. Try the effect of picric aniline blue on 
these and other parts of the bundle. Apply 
Schulze's solution to other sections, and phloro- 
glucin (followed by hydrochloric acid) to still 
others, and note the results. What parts of the 
bundle are lignified? How about other parts of 
the stem ? 
3. The fundamental tissue. Examine the large cells 
composing the tissue, using both transverse and 
longitudinal sections. Ascertain whether the large 
cells of which it is made up present the same 



46 \ OF COMMON PLANTS. 

appearance and structure in all parts of the stem. 
Test the contents for starch. 

V. Having become acquainted with the minute anatomy 
of the stem, study it from a mechanical point of view, 
endeavoring to ascertain whether the thick-walled me- 
chanical elements are grouped in such a way as to secure 
strength with economy of material. Notice the disposi- 
tion of the heavy sub-epidermal tissue in a continuous 
hollow cylinder, the arrangement of the fibro-vascular bun- 
dles, and the way in which the elements composing the 
bundle-sheath are distributed. 1 

VI. Stem of white pine. The structure of the stem of 
conifers presents various interesting peculiarities, but the 
arrangement of the parts and mode of growth are nearly 
identical with those of dicotyledonous stems, and, moreover, 
have been so fully treated in a number of laboratory guides 
as to render it unnecessary to repeat directions for their 
study. The student is recommended, however, to carry 
out substantially the same plan of work on the stem of the 
white pine as is outlined in the section on the Scotch pine 
in Arthur, Barnes, and Coulter's Plant Dissection. 

VII. Cambium. Nearly all woody species in temperate 
regions of the globe form distinct annual rings which 
mark the growth of the wood from year to year. In order 
to understand the process a study of the cambium should 
be made. Shoots of the white pine four or five years old are 
suitable for this purpose. They should be cut during the 
season of active growth, say from June to August, and 
placed in alcohol. If properly hardened, transverse sec- 
tions may be obtained that show very perfectly the new 
wood and bark formed by the division of the delicate 

1 Cf. Strasburger, Practical Botany, p. 88, and footnote. 



THE STEM. 47 

cambium cells. Test for lignin, and study the mode of 
development of the wood. 1 

PHYSIOLOGY OF THE STEM. 
Protection. 

I. Examine under a lens the stem of the cultivated 
verbena, primrose, and other plants from the greenhouse. 

II. Mount portions of the epidermis of each in water, 
and examine with the compound microscope. Draw and 
describe the various epidermal appendages. 

III. Make a careful study of the protective arrange- 
ments of the common thistle, teasel, honey locust, cactus, 
and blackberry. Ascertain the morphological character 
of their various protective structures. 

IV. Examine various woody stems, such as those of the 
hickory and oak. Notice 

1. The thickness of the bark. 

2. How it accommodates itself to the growth of the 

tree. 

V. Enumerate any other means that you have observed 
by which the stems of plants are protected. 

Mechanical Support. 

I. Study the arrangement of the wood elements of the 
stem of the common elder. Compare it with a stalk 
of wheat; with the stem of a palm. Is the material 
economically employed ? 

II. Make a transverse section of the stem of coleus. 
Examine with the low power of a compound microscope. 

1 In connection with his study of the structure of stems, the student 
should read Gray's Structural Botany, pp. 67-82. 



48 STUDY OF COMMON PLANTS. 

Draw an outline sketch, locating the position of the me- 
chanical elements. 

III. Cut through an old tendril of a grape-vine. Notice 
the disposition of the wood elements. Test its strength. 

IV. Study under the compound microscope the bast 
fibers of basswood and other common plants. 

V. Write a brief account of what you have ascertained 
regarding the mechanical arrangements for the support of 
the plant. Read Goodale, Physiological Botany, pp. 188- 
194 ; Haberlandt, Physiologische Pflanzenanatomie, p. 96 

et seq. 

# 

Transportation of Food in Solution. 

I. Cut a short branch from a grape-vine. Immerse the 
cut end in a colored solution, such as red ink. After 
some time make transverse sections, and observe how far 
and through what parts of the stem the colored fluid has 
penetrated. 1 

II. Repeat the experiment, using a fresh leafy stem of 
Tradescantia for the purpose. Place finely powdered 
indigo in the water and allow the plant to be exposed to 
sunlight. This time take the precaution to cut 4 the stem 
under water so as to prevent the entrance of air. If the 
cut is made slanting, and the whole operation skillfully 
performed, the particles of indigo can be seen under the 
compound microscope as they enter the vessels of the 
Tradescantia. 

Storage of Food. 

I. Cut a common potato in two. Make thin sections 
from the exposed surface, and examine with the compound 

1 On the ascent of water in woody plants, see H. Marshall Ward, Tim- 
ber and Some of its Diseases, Chap. IV (Nature Series). 



THE STEM. 49 

microscope. Draw one or two cells with their contents, 
taking care to show details of structure. 

II. Examine in the same way sections from various 
other underground stems, such as ginger, mandrake, etc. 

III. Prepare sections from pieces of a dahlia "tuber" 1 
that have lain in commercial alcohol for some weeks. 
Draw a few cells, showing the peculiar sphere-crystals of 
inulin. 

IV. In some stems, as, for example, an onion bulb, sugar 
is stored. This may be tested for in the way described by 
Strasburger, Practical Botany, p. 48. 

MODIFIED STEMS. 

I. Make a thorough study of the common potato, ob- 
taining for the purpose a number of different varieties. 
What reasons are there for considering it a stem rather 
than a root? What are the "eyes"? Where are they 
most abundant? Are they all alike? Find where the 
potato was attached. Draw an outline and indicate by 
a dotted line the direction of growth in length. Does it 
ever branch ? Cut a transverse section so that it will 
pass through a bud. Indicate in an outline sketch the 
position of pith, wood, and bark. Notice that the wood 
has been reduced to a minimum.- It appears to the naked 
eye as a faint circular line. 

Write a complete description, and discuss the mor- 
phology of the potato. See Gray, Structural Botany, p. 59. 

II. Study a collection of other modified stems in the 
same way, endeavoring in each case to satisfy yourself as 

1 This is really a root, but on account of its convenience it is selected 
instead of a stem. 



50 STUDY OF COMMON PLANTS. 

to every morphological feature. The following and a 
considerable number of additional species can usually be 
obtained, — some at the florist's, others at the grocery, and 
still others at the drug store : ginger, iris, geranium, onion, 
crocus, Solomon's seal, aconite, calamus. Fresh indigenous 
plants will furnish many more. 

III. Examine specimens of as many of the following 
genera as are procurable, and discuss their morphology: 
Muhlenbeckia, Myrsiphyllum, Ruscus, Asparagus. 

In such exercises, a hasty examination of external feat- 
ures is by no means sufficient. Every species taken in 
hand should be subjected to patient and thorough study. 
Some of those named present difficulties that are not likely 
to be overcome by a student who is unwilling to think. 



GROWTH OF STEMS FROM BUDS. 

I. Obtain, before they have opened in spring, well- 
developed buds of lilac, maple, hickory, horse-chestmit, 
Austrian pine, and other trees. Study them carefully 
with regard to protective arrangements, taking account 
of the structure and position of the bud-scales (imbri- 
cated like the shingles of a roof), waterproofing, hairs ; 
in short, whatever appears to contribute to the protec- 
tion of the parts within. What part of the bud is best 
protected ? 

II. Study next the arrangement of the parts composing 
the bud, taking first the buds of the lilac, and following 
with those of the horse-chestnut and other trees. Remove 
the bud-scales and undeveloped leaves in succession, and 
lay them in radiating rows, following the order in which 
they are placed in the bud. 



THE STEM. 51 

Is the arrangement of the parts of the bud advantageous 
as regards economy of space ? Does it present any other 
advantages? 

Compare the last year's growth of the stem with the ter- 
minal bud, bearing in mind that " a bud is an undeveloped 
branch." 

III. Examine all the marks on a horse-chestnut branch. 
Three kinds of scars are to be seen : namely, those left by 
the foliage leaves, by bud-scales, and by flower-clusters. 
Compare all these with each other and with what is seen 
in the terminal bud, until you are thoroughly familiar with 
the characters of the branch as they appear in the bud. 
Carry out a similar study with the buds and branches of 
other trees. 1 

IV. Place the cut ends of shoots of lilac, horse-chestnut, 
apple, etc., in water, the latter part of winter ; keep them 
in a warm room, changing the water frequently, and ob- 
serve the unfolding of the buds. Notice the first observa- 
ble changes as well as those occurring in later stages. 
Record your observations in detail. 

V. Compare the terminal buds of plants belonging to 
different genera, e.g. Acer, Carya, and Pinus, and deter- 
mine whether each presents distinctive marks. Next, 
compare the buds of the red, and sugar maple, noting 
carefully all the differences. In the same way, compare 
the buds of Austrian, Scotch, and white pine, of the black 
walnut and butternut. 

As opportunity offers, practice the identification of trees 
in winter by means of buds and other parts. 2 

1 For an admirable study of the buds and branches of common trees, 
see Newell, Outlines of Lessons in Botany, Part I. Ginn & Co. 

2 Cf. Foerste, Bot. Gaz., XVII (1892), p. 180. 



52 STUDY OF COMMON PLANTS. 



REVIEW AND SUMMARY. 

The stems of plants exhibit certain inherited pecu- 
liarities of form, structure, and habit. In some large 
families, the mints, for example, the stem is 

rorm, # m ^ 

structure, square ; while in others, as the true sedges, it 
is triangular. The cylindrical form, however, 
which has important mechanical advantages in its favor, 
is most common. Characteristic habits, manifested in 
mode of growth or choice of surroundings, are also fre- 
quently met with. Thus, the family to which the morn- 
ing-glory belongs is particularly distinguished by its 
climbing habit, the members of the water-lily family by 
their aquatic habits, and so on. Structural peculiarities 
are still more distinctive and far-reaching ; so that, as a 
rule, we readily determine the class to which a plant 
belongs by ascertaining the arrangement of the tissues 
composing the stem. 

The texture of the stem, as determined by the nature 
of its elements, is often characteristic. Various families 
Texture and °^ plants, as those to which the maple, oak, 
duratiou. a nd willow belong, have woody stems ; while 
others, as the pink and violet families and many others, 
are herbaceous. The duration of the plant corresponds 
rather closely to the nature of the stem. Woody plants 
are perennial, living for an indefinite period, while herba- 
ceous ones are commonly annual or biennial. These dis- 
tinctions, however, are not to be pressed too far, since the 
texture of the stem is subject to much variation, even in 
the same species, and duration is greatly influenced by 
climatic conditions. 

While typical stems are distinguished by the various 
characters already referred to, there are many others that 



THE STEM. 53 

have taken modified forms corresponding to special func- 
tions that they have assumed. Thus many stems, Modified or 
a large proportion of which are subterranean, derived forms. 
serve chiefly as reservoirs of reserve materials, and in the 
course of time have undergone striking modifications both 
of form and structure. The tuber of the common potato 
shows all the essential characters of a dicotyledonous stem 
in the formation of buds, the concentric arrangement of 
pith, wood, and bark, and in still other respects, but the 
fibrous tissue has almost wholly disappeared, while the 
cellular tissue has increased to such an extent as to give 
the tuber the appearance of a monstrosity compared with 
the ordinary branches of the same plant. Quite as strik- 
ing changes are seen in branches that have taken the form 
of spines and assumed the function of protection. Good 
examples of these are the spines of the hawthorn and 
other familiar plants. Even more remarkable modifica- 
tions are presented in the leaf-like organs known as 
cladophylls. In the case of the so-called smilax of the 
greenhouses, the true leaves are inconspicuous scales, 
while the cladophylls so perfectly simulate foliage leaves 
as to deceive an inexperienced eye. Much caution is 
necessary in studying the morphology of these and other 
modified branches. Their position on the stem, structure, 
and mode of growth, and any tendency they may exhibit 
to become ordinary leaf-bearing shoots, are all to be taken 
into account. 

In their anatomical structure and mode of growth, stems 
present well marked peculiarities, which, as already stated, 
are sufficiently characteristic to admit of the Anatomical 
ready determination of the great class to which stn J ctu J e and 

J & mode of 

a plant belongs. The stems of a large propor- growth. 
tion of monocotyledons are well represented by that of 



5i STUDY OF COMMON PLANTS. 

Indian corn. In this the fibro-vascular bundles are scat- 
tered through the fundamental tissue so that there is no 
Monocotyle- manifest distinction of pith, wood, and bark, and 
douSi both here and in other members of the same 

class certain mechanical arrangements of much interest 
present themselves. In the stem of Indian corn a strong 
cylindrical band of sclerenchyma is placed just beneath 
the epidermis, a disposition of the mechanical elements 
adapted to secure the greatest strength with the least 
amount of material; and the same principle is carried out 
in the bundles themselves, the sheaths of which are much 
thickened radially, thus aiding materially in preventing 
bending of the stem, and also protecting the vessels and 
other conducting elements. 

The stem of dicotyledons presents a rather more com- 
plicated structure. As seen in the apple shoot, which 
may be taken as a representative, the pith, 

Dicotyledons. -, -i i i i , • -n 

wood, and bark are arranged concentrically. 
In the bark, as a rule, three layers may be distinguished, 
viz., outer bark or cork, middle bark or green layer, con- 
sisting chiefly of large cells containing chlorophyll and 
other materials, and inner bark or bast, characterized by 
the presence of sieve-tubes, usually with bast fibers and 
some parenchyma, Between the inner bark and wood is 
the cambium zone, which during the growing season is a 
layer of delicate cells, by the multiplication of which new 
wood and bark are produced. The wood consists of the 
large vessels, the openings of which are conspicuous on 
transverse section, wood fibers which constitute the 
greater part of its substance and give the wood its 
rigidity, and the medullary rays, to which in mairy species 
are added the wood-parenchyma cells. The pith consists 
of large cells which commonly present no distinctive 



THE STEM. 55 

peculiarities. Since each year, in temperate regions, the 
stems of dicotyledons add a new zone of wood, it is 
possible to determine the age of a tree by counting the 
number of annual rings. Not infrequently the record 
is obscured by irregular growth, due to drought and 
other causes, but in general these rings are clearly defined. 

In their mode of growth the stems of gymnosperms 
agree with those of dicotyledons, but their wood elements 
are peculiar, the wood being composed mainly 
of elongated cells called tracheids, the radial F 1111108 ? 61,1118, 
sides of which have numerous bordered pits, by means 
of which they communicate with each other and with the 
medullary rays. 

The structure of stems corresponds with a number of 
very important functions performed by the elements that 
compose them. Thus the epidermis, afterwards 
replaced by cork, is protective, as is also the 
bark, which on the trunks of most trees becomes greatly 
thickened with advancing age. The medullary rays and 
other parenchyma cells of wood and bark serve for storage 
of various food products, and are also employed to a consid- 
erable extent in conducting them from one part of the plant 
to another. Bast and wood fibers serve a special purpose 
as mechanical elements by which the stem is maintained 
in its position, and enabled to resist forces that tend to 
strain or fracture it. Finally the vessels and tracheids are 
chiefly concerned in conducting water containing mineral 
substances and air from the roots to the upper parts of the 
plant, while the sieve-tubes of the inner bark store up 
nitrogeneous food materials, and convey them to the points 
where they are needed. 

It will, of course, be understood that an adequate 
account of the physiology of stems cannot possibly be 



56 STUDY OF COMMON PLANTS. 

condensed into such a summary statement as the fore- 
going ; but it will at least serve to point out the important 
parts played by the various elements of the stem as they 
contribute, each its share, to the work of the whole. The 
mechanical system is treated at length by Haberiandt, 
Physiologische Pjianzenanaiomie, pp. 96-143, and an ex- 
tended review of the theories regarding the ascent of 
water in the trunks of tall trees is given by H. Marshall 
Ward, Timber and Some of its Diseases, Chap. IV. 



THE LEAF, 57 



V. THE LEAF. 

MATERIAL REQUIRED. 

Leaves of as many kinds as are procurable. See suggestions under 
"Systematic Description." Branches of basswood, elm, maple, 
and horse-chestnut. Leafy plants of primrose, fuchsia, dandelion, 
and geranium. 

Leaves of hyacinth and English ivy. 

Leaves of various hairy plants and of conifers, rushes and sedges, etc. 

Leaves of different ferns and flowering plants called for under "Me- 
chanical and Conducting System." 

Specimens of Elodea Canadensis growing in water, and of Mnium or 
other common moss. 

Tropaeolum and other convenient plants growing in pots 

A collection of modified leaves. 

SYSTEMATIC DESCRIPTION. 

Write a careful and complete description of the leaves 
of ten or a dozen different plants, following, as far as it 
proves serviceable, the schedule given below. 

Some one has said that " there is no part of botany so 
overwhelmed with cumbrous terminology as that which 
relates to leaves." Nevertheless the really necessary 
terms are easily learned, and the peculiarities expressed 
by them are far from accidental. The form of the leaf, its 
position on the stem, the venation and other structural 
features are generally such as to secure the greatest effi- 
ciency, and in studying these it is desirable to be able 
to express one's self with exactness. The greenhouse or 



58 STUDY OF COMMON PLANTS. 

window garden, the drug store, collections of preceding 
years, and seedlings raised in the laboratory will, even in 
winter, furnish abundant material. The following may be 
suggested as a partial list : English ivy, geranium, prim- 
rose, verbena, rose, oxalis, maurandia, nasturtium, oak, 
maple, elm, lily, Indian corn, hyacinth, amaryllis, arbor 
vitse, hemlock, juniper, and different species of pines. 

Schedule for Leaf Description. 

1. Position, Radical 2 or cauline. 

2. Arrangement, Opposite, alternate, whorled, fascicu- 

late. 

3. Relation to Stem, Petiolate, sessile, perfoliate, 

sheathing, connate, decurrent, etc. 

4. Stipules, Described as leaves. If absent, the leaf is 

said to be exstipulate. 

5. Form, Acicular, awl-shaped, linear, oblong, ellipti- 

cal, oval, rotund, ovate, lanceolate, reniform, 
obovate, oblanceolate, etc. 

6. Apex and Base, For special terms see dictionary and 

text-books. 

7. Margin, Entire, serrate, dentate, crenate, sinuate, 

irregular, lobed, cleft, parted, divided, etc. 

8. Venation, Pinnate, palmate, parallel. 

9. Surface, Glabrous, glaucous, pubescent, wooly, vil- 

lose, hirsute, prickly, etc. (These terms apply also 
to the surface of other organs.) 
10. Compound Leaves, Pinnate, bi-pinnate, tri-pinnate, 
palmate, bi-palmate, tri-palmate, pinnately or pal- 
mately decompound, etc. 

1 Gray's Lessons, Section 7, and illustrations of botanical terms in 
Webster's International Dictionary should be consulted. 

2 A misleading term, but fixed in the language. 



THE LEAF. 59 



LEAF ARRANGEMENT. 

I. Take branches of basswood, elm, maple, and horse- 
chestnut, and study the leaf arrangement. In winter the 
position of the leaves of preceding years may be deter- 
mined by the leaf-scars. 

Are the leaves placed advantageously as regards expos- 
ure to light? Cf. Lubbock, Flowers, Fruits, and Leaves, 
pp. 103-114. 

II. Compare other plants, e.g. primrose and fuchsia, 
dandelion and geranium, with regard to this principle. 

III. Try the effect of putting the leaves of one species 
on the branches of another, without changing the leaf 
arrangement. 

MINUTE ANATOMY. 

I. With a pair of fine forceps strip off a portion of the 
epidermis of a hyacinth leaf. Mount in water and examine 
under the high power of a compound microscope. Observe 

1. The elongated epidermal cells destitute of chlorophyll. 

2. The stomata, each with two reniform guard-cells con- 

taining chlorophyll bodies. Draw. 

II. Place a small portion of a leaf of the English ivy 
between two pieces of pith, and, with a keen razor, cut a 
number of transverse sections. Examine under the com- 
pound microscope. Select a section that shows all the 
structural details and draw accurately. Beginning with 
the upper surface the section shows 

1. The upper epidermis, consisting of a single layer of 
thick-walled cells, destitute of chlorophyll. 



60 STUDY OF COMMON PLANTS. 

2. A layer or two of closely packed cells, with their 

long diameter perpendicular to the surface of the 
leaf, containing many chlorophyll bodies, These 
constitute the palisade tissue. 

3. Other chlorophyll-bearing cells essentially the same as 

the preceding, but less regular in shape and more 
loosely arranged, so that toward the lower surface 
of the leaf large openings, intercellular passages, 
occur. Some of these cells contain large stellate 
ciystals of oxalate of lime. 

4. About midway between the upper and lower surface, 

the veins, fibro-vascular bundles, cut either trans- 
versely or at an angle, according to their direction 
at the place where the section is made. The 
thick-walled mechanical elements constitute the 
bundle-sheath. The bundle itself is divided into 
two adjacent parts, the xylem lying towards the 
upper surface of the leaf, and the phloem towards 
its lower surface. The tracheids of the xylem, 
elongated tube-like structures, are easily recog- 
nized. 

5. The lower epidermis, similar to the upper, but with 

stomata at frequent intervals. These are placed 
so that each one forms an entrance to one of the 
intercellular passages. (Sections of the stomata 
are best studied in a hyacinth leaf.) 

Note. — The different sections should be studied until the gen- 
eral structure of the leaf is thoroughly understood. Every fact is 
of physiological significance, and it is of the utmost importance 
that the student should have a complete and clear knowledge of 
the minute anatomy based on direct observation. 



THE LEAF. 61 



PHYSIOLOGY OF LEAVES. 
Protection. 

Leaves require protection against 

1. Changes of temperature. 

2. Drying. 

3. Attacks of animals, fungi, etc. 

4. Injury by wind and other meteorological agencies. 

Cf. Lubbock, Floivers, Fruits, and Leaves, Chap. 
VI ; Kerner, Flowers and their Unbidden Guests. 

Some of the following observations are to be carried out 
in the laboratory, while others are best conducted out of 
doors. 

I. Remove the epidermis from a portion of a hyacinth 
leaf, or the leaf of some other fleshy plant. Notice its 
texture, strength, and elasticity. After a time observe 
any changes that have taken place in the part from which 
the epidermis has been removed. 

II. Examine the hairy covering of leaves of common 
mullein. Compare other hairy plants. Examine micro- 
scopically the hairs of mullein, verbena, rose geranium, and 
other common species. Make a series of drawings illus- 
trating the epidermal appendages of various leaves. 

III. Study the leaves of the Austrian pine, common 
juniper, and other conifers. Enumerate the protective 
arrangements exhibited by them. 

IV. Compare very young leaves of the oak, apple, or 
other common tree, with older ones. 

V. Many plants are protected by disagreeable or poi- 
sonous substances stored in their foliage. Name any of 
these that you know. 



62 STUDY OF COMMON PLANTS. 

VI. Some leaves exhibit remarkable "sleep move- 
ments." What are these for? Cf. Darwin, Power of Move- 
ment in Plants, Chap. VII. 

VII. Other leaves exhibit equally remarkable u hot sun 
positions." Of what use are these to the plant? Cf. Wilson, 
Contributions from the Bot. Lab. Univ. of Pa., Vol. I, No. 1. 

Mechanical and Conducting' System. 

The skeleton or framework of the leaf serves to support 
the delicate green tissue, holding it so as to expose the 
largest possible surface to the sun, and, at the same time, 
giving the whole structure sufficient rigidity, strength, and 
elasticity to resist mechanical violence. It also serves to 
conduct a constant supply of water and mineral substances 
to every part of the leaf, and to convey away elaborated 
food materials. It is only by keeping these principles in 
mind that an intelligent study of venation can be made. 
Cf . Sachs, Physiology of Plants, pp. 48-53. 

I. Obtain the leaves of several ferns, e.g. Adiantum pe- 
datum, Asvidium cristatum, Osmunda Claytoniana. Draw 
an enlarged outline of a leaflet of one or more species, 
showing the exact position of the veins. 

II. Compare the venation of a number of monocotyle- 
dons, e.g. Tradescantia, Alisma, Sagittaria, Pontederia, 
Calla, Arissema, Smilax. Draw accurately one or more 
leaves. 

III. Examine the venation of the leaves of Catalpa, 
Liriodendron, Fuchsia, and Nymphsea. How does it 
compare from a mechanical standpoint with that of the 
leaves previously studied ? 

IV. Study critically the structure of the leaf of a black 
oak or red oak. Measure the widest space you can find 



THE LEAF. 63 

that is free from veinlets. Do these end freely or anas- 
tomose ? Is there any apparent advantage in this ? 

Assimilation. 

The chief and characteristic function of green leaves is 
assimilation, that is, the production of organized food sub- 
stances. 

I. Examine the leaves of Elodea Canadensis under the 
compound microscope. Study the form and position of 
the chlorophyll bodies contained in the cells. Are they 
equally numerous in all parts of the leaf ? Draw two or 
more cells showing the chlorophyll bodies in place. Com- 
pare with these the chlorophyll bodies of Mnium or other 
common moss. 

II. Take fresh leaves of the Elodea that has been 
growing in a jar of water exposed to sunlight. Place 
them in strong alcohol and allow them to remain until 
they have lost their color and the alcohol has turned 
green. Mount for microscopic study and test with iodine 
solution. Starch should be found in the chlorophyll 
bodies. It may be demonstrated still more easily in the 
chlorophyll bands of Spirogyra and other filamentous 
algae. 

III. By an experiment best performed by the teacher 
or by a pupil specially appointed, the necessity of light for 
the production of starch, and the local nature of the pro- 
cess of assimilation is demonstrated. Take a healthy 
Tropaeolum (" nasturtium ") growing in a flower pot, and 
place it in the dark for two or three days. Test one of 
the leaves for starch, which by this time should have 
disappeared. Now place the plant where it will be exposed 
to the bright sunlight, having previously covered a part of 



64 STUDY OF COMMON PLANTS. 

one or more of the leaves so as to exclude the light by 
pinning flat pieces of cork closely on opposite sides. After 
the plant has been in the light for a day or more, proper 
tests show that starch has been formed in the parts of the 
leaves exposed to light but is absent where they were 
covered (except in the fibro- vascular bundles). Further 
details are given by Detmer, Das pflanzenphysioloyische 
Praktikum, pp. 33-34 and 37-38. 

IV. Place an inverted funnel over a lot of Elodea, 
growing in a glass jar, and push it down until the small 
end of the funnel is beneath the surface of -the water. 
Fill a test-tube with water, stop it with the thumb, invert, 
and (under water) bring the small end of the funnel into 
it. Set the apparatus where it will be in bright sunlight. 
Observe the bubbles of gas given off by the plant. After 
enough has been collected in the tube, test for oxygen. 
This may be done by lighting a match and blowing it out, 
and then inserting it, while still glowing, into the test- 
tube. 

V. The preceding observations show that starch is 
formed in the chlorophyll bodies in the presence of sun- 
light, and that during the process oxygen is given off. 
By means of a simple experiment it may also be shown 
that starch is not thus produced unless carbon dioxide is 
supplied to the plant. The teacher will find the apparatus 
figured and described by Detmer, Praktikum, p. 38, easily 
made and entirely satisfactory. 

Transpiration. 

I. Take a quantity of green leaves and place them in a 
wide-mouthed bottle. After a time observe the moisture 
that has collected on its inner surface. Where has it 
come from ? 



THE LEAF. 65 

II. Cut off a strong, well-developed leaf of a primrose, 
immerse the blade of the leaf in water, and placing the 
cut end of the petiole in the mouth, inhale forcibly. Do 
you obtain any proof that the inside of the leaf is in com- 
munication with the atmosphere ? 

III. Take any leafy plant of convenient size that is 
growing in a flower pot, cover the pot with a piece of 
dentists' rubber, bringing it up around the stem of the 
plant and tying it so that no water can be given off 
except through the plant itself. Weigh the whole, and at 
the end of twenty-four hours weigh again. To what is the 
loss of weight due ? 

IV. Vary the last experiment by employing different 
kinds of plants, as, for example, some with leathery and 
others with soft leaves ; also by placing some in the sun- 
light and others in the shade, in the open air and in a 
closed room. What are some of the conditions affecting 
transpiration? 

Respiration. 

Respiration is a function of every living cell. Hence 
leaves are to be thought of as organs of respiration in so 
far as they expose a very large number of active cells to 
the atmosphere, although they do not really " correspond 
to the lungs of animals." We may therefore employ 
leaves to demonstrate the process of respiration, or we 
may use flowers or germinating seeds. 

Take three wide-mouthed bottles and fill each two-thirds 
full, the first of fresh leaves, the second of germinating 
peas, and the third of flowers. Cork and allow to stand a 
few hours. Test the air in the bottles at the beginning 
and close of the experiment by introducing a homoeopathic 
vial containing limewater, also by inserting a lighted 
match. What is the result ? 



66 STUDY OF COMMON PLANTS. 

Note. — The student should carefully consider what is taking place in 
the cells of green leaves, inasmuch as a great deal of confusion has arisen 
through lack of clear conception and expression. Since they respire like 
other parts of the plant, leaves absorb oxygen and give off carbon dioxide 
both day and night. On the other hand, as organs of assimilation, they 
decompose carbon dioxide in the sunlight, giving off oxygen and employ- 
ing the carbon in the production of starch. A complete discussion of the 
subject would require much space, but the fundamental facts are as 
stated above, and should be firmly fixed in mind. 



MODIFIED LEAVES. 

When some other function than that of assimilation 
becomes predominant, leaves exhibit marked, and in some 
cases extremely peculiar, modifications. 

I. Examine shoots of the common barberry. Determine 
the morphology of the spines and give reasons. Compare 
the spines of the common locust. Are they the same 
morphologically as those of the barberry ? Examine dif- 
ferent species of cacti and determine the morphology of 
the parts. 

II. Study the tendrils of such of the following plants as 
can be obtained and ascertain which of them are to be 
classed as leaves or parts of leaves: Smilax rotundifolia, 
Cobcea scandens, Adlumia cirrhosa, Echinocystis lobata, 
grape-vine, pea, cucumber, etc. Note particularly any cases 
in which only partial modification has taken place. Cf. 
Darwin, Climbing Plants, Chaps. Ill, IV. 

III. Leaves of insectivorous plants. See Special 
Studies. 

SPECIAL STUDIES. 

I. Correlation of the forms of leaves with their position 
on the stem. See Lubbock, Floivers, Fruits, and 

Leaves. 



THE LEAF. 67 

II. Extent of leaf surface. Measure accurately the 
superficial area of an average leaf of a geranium or 
other common plant, and estimate its entire 
leaf surface. 

III. Generic and specific characters drawn from leaves. 

IV. Variability. Compare the leaves of any individual 

plant, a rose bush, for example, and observe their 
different forms. 

V. Leaves of insectivorous plants. Drosera rotandifolia 
is widely distributed and is easily cultivated in the 
laboratory. It is a most valuable plant for pro- 
longed observation and experiment. Cf. Darwin, 
Insectivorous Plants. 



REVIEW AND SUMMARY. 

The leaf is the most characteristic, and, in some respects, 
the most important part of the plant. The venation and 
various peculiarities of form and structure are ^ohMMteT- 
usually sufficient to indicate at once the class, isticpartof 
and not infrequently the genus or species to e p an ' 
which a plant belongs. Even those who have had no 
special botanical training readily distinguish the oak, 
willow, maple, and various other plants by the leaf alone. 
Hence in determining relationships special attention is 
given to characters drawn from leaves, and it becomes 
necessary to define these with care and precision. Physio- 
logically, too, the leaf is engaged in work peculiar to 
plants, work of a nature that cannot be performed by 
animals, and upon which they are dependent for their 
continued existence on the globe. A clear conception, 



68 STUDY OF COMMON PLANTS. 

therefore, of the general facts of leaf structure and physi- 
ology is essential to an understanding of some of the most 
fundamental facts of biological science. 

Beginning with form and position, we have seen that, 
as a rule, leaves are so constructed and placed as to secure 
Form and the exposure of a large surface to the air and 
position, light. The blade of the leaf is raised on a 

petiole whenever this is necessary to more readily accom- 
plish the end to be attained. Furthermore, the position of 
leaves on the stem is such as to aid in securing the great- 
est exposure. If we inspect a large tree in full foliage, 
such as a maple or basswood, it will be seen that the leaves 
are placed so as to result in a minimum of interference 
with each other. It will also be noticed, as Sir John 
Lubbock points out, that there is a manifest correlation 
between the form of the leaves and their arrangement on 
the branch, so that in many cases it would be a decided 
disadvantage to replace the leaves of one species by those 
of another unless the leaf arrangement were changed. 
Further, an examination of buds that have not yet opened 
shows that the leaf arrangement is such as to economize 
space. These two principles, compact disposition in the 
bud, and a position on the stem that will secure full expos- 
ure of leaf surface, are the determining factors in the 
arrangement of leaves. 1 

An examination of the anatomical structure of an ordi- 

1 Incidentally it results that the leaf arrangement of many plants is so 
definitely fixed that it may be expressed by a mathematical formula. 
Phyllotaxis, however, as usually presented, is a curious rather than a 
fruitful study. ' ' We must now acknowledge that there is no general 
law which can be formulated for the arrangement of the organs on a 
parent axis ; that, on the contrary, according to circumstances in each 
case, special causes determine whether the relations of position turn out 
to be this or that." — Sachs, Physiology of Plants, pp. 500, 501. 



THE LEAF. 69 

nary foliage leaf shows that both surfaces are protected by 
an external layer of cells constituting the epi- Anatomi al 
dermis. The outer wall of the epidermal cells structure. 
is commonly thickened, and by taking on a pi ermls ' 
layer of cutin or wax becomes nearly or quite impervious 
to water. The leaves of some plants, particularly of species 
growing in tropical regions, have more than one layer of 
cells composing the epidermis, thus securing more efficient 
protection. The cells of the epidermis are, for the most 
part, destitute of chlorophyll, but contain a large quantity 
of water which is absorbed as required by the delicate cells 
in the interior of the leaf. Additional protection is often 
afforded by hairs which thickly cover the leaves of many 
species, particularly those growing on the steppes and 
other parts of the globe where vegetation is subject to 
sudden and extreme changes of temperature. Finally, 
protection is not infrequently secured by diminishing the 
amount of leaf surface, as seen in many shrubs, and in 
desert grasses and sedges with cylindrical leaves. 

Communication with the interior of the leaf is secured 
by means of numerous openings called stomata. These 
are provided with guard-cells, commonly of the 
same general form as those of the hyacinth leaf, 
which act as a valve, opening in sunlight while the leaf is 
at work and closing, or partially closing, at night. The 
mechanism, apparently simple, is, in reality, rather diffi- 
cult of complete explanation. 1 The essential fact is that 
by means of the stomata a free interchange of watery 
vapor and gases between the interior of the leaf and the 
surrounding atmosphere is effected, and that by means 
of the guard-cells this interchange is obstructed when the 
external conditions are unfavorable. 

1 Cf . Sachs, Physiology of Plants, pp. 248-251. 



70 STUDY OF COMMON PLANTS. 

The internal structure of the great majority of leaves 
is essentially the same as we have seen in the English ivy. 
Fibro-vascn- The midrib and veins, composed of fibers and 
lar bundles, tracheids, present a strong frame-work by means 
of which all the parts are supported, and which also serves 
as the conducting system of the leaf. The green parts 
consist of chlorophyll-bearing, parenchyma cells, the chief 
function of which is the manufacture of organized food 
substances. An extended comparison of the leaves of 
Assimilating many species of plants shows several interesting 
cells. arrangements for bringing the assimilating cells 

into an advantageous position as regards the light. In the 
first place, the leaf itself " turns towards the light," i.e. 
places itself so that the upper surface is perpendicular to 
the incident rays. In the second place, the palisade cells 
are themselves nearly perpendicular to the leaf surface, a 
position in which their contents are brought into relation 
with the light, without, however, cutting it off entirely 
from the cells below. Finally, the chlorophyll bodies 
vary their position in the cells according to the intensity 
of the light, ranging themselves so as to expose as large a 
surface as possible when the illumination is feeble, and a 
less surface when it is too intense. 1 In addition to these 
arrangements with reference to light, the assimilating cells 
are grouped in such a manner as to facilitate the convey- 
ance of water to them by the fibro-vascular bundles, and 
the removal of elaborated food substances through the 
same channels. 2 

It is thus seen that the leaf is an extremely delicate 
organ, adapted to the performance of certain important 
functions. Their first and most characteristic function 

1 Sachs, I.e., p. 617 et seq. 

2 Haberlandt, Physiologische Pflanzenanatomie, p. 184 et seq. 



THE LEAF. 71 

is the formation of organic food products oat of the crude 
substances taken in from the atmosphere and F unc tions. 
soil. In the presence of sunlight starch is Assimilation, 
produced in the chlorophyll bodies. The materials from 
which it is formed are carbon dioxide, obtained from 
the atmosphere, and water brought up from the roots. 
The starch accumulates in the daytime in the cells where 
it is formed, and afterwards is conveyed away in a soluble 
form to the various reservoirs of reserve materials. Simple 
experiments have shown the conditions under which the 
formation of starch takes place and the attendant phe- 
nomena. The rapid evolution of oxygen seen when a 
water plant is allowed to stand in bright sunlight is at 
once checked when the vessel containing it is brought 
into the shade. The oxygen is given off in the formation 
of starch and this process ceases when light is wanting. 
Again, if the water in which the plant is growing is boiled 
so as to expel the carbon dioxide, it is observed that the 
evolution of oxygen ceases as in the preceding experiment, 
but for a different reason. The carbon dioxide being 
wanting, the leaves are deprived of the carbon necessary 
to the production of starch. 

Water in relatively large quantities is required to carry 
to the leaf, and to the other parts of the plant, the sub- 
stances used in the formation of starch and Transpira- 
other products. The surplus water is evapo- tioiu 
rated by the leaves. By simply weighing at stated inter- 
vals a plant arranged so that evaporation can take place 
from no other part, it is found that large amounts of 
watery vapor are given off through the leaves. Transpira- 
tion, then, or the evaporation of water, is another important 
function of leaves, since the water thus given off is the 
vehicle of transportation of the various substances used by 
the plant. 



72 STUDY OF COMMON PLANTS. 

Still another function which the leaf shares with other 

living parts of the plant, and which is characteristic of all 

living cells whether plant or animal, is that of 

Eespiration. . . -, P . , , 

respiration. As we nave seen, one ot the prod- 
ucts of respiration, carbon dioxide, is easily demonstrated 
by testing with lime water the air within a bottle contain- 
ing a quantity of green leaves. The abundant precipitate 
of carbonate of lime shows that the leaves are giving off 
carbon dioxide in considerable quantity, and as this is true 
whether the experiment is performed in the daytime or at 
night, we infer that respiration is going on continually. 
It should be said, however, that, contrary to a widely 
spread popular belief, the quantity of carbon dioxide 
exhaled by plants is so small in comparison with what is 
given off in animal respiration that it may be disregarded 
in connection with the question of keeping house plants. 
They are a decided advantage in the home from a sanitary, 
as well as aesthetic, point of view. 

The chief functions of the leaf, then, are 

1. Assimilation, or the production of organized material. 

2. Transpiration, or the evaporation of water that has 
served as a vehicle for the transportation of crude sub- 
stances. 

3. Respiration, a process common to all living things. 

The first of these takes place in sunlight, or its equiva- 
lent ; the second is most active in the daytime, but is not 
limited to it ; and the last continues both day and night, 
as long as the leaf is alive. 

We have learned in our study of the barberry and a 
number of other familiar plants, that leaves are subject to 
various modifications corresponding to other than their 
ordinary functions. These modifications are not infre- 



THE LEAF. 73 

quently so profound that it becomes a matter of no little 
difficulty to pronounce upon the morphological Modified 
character of a particular structure. Spines leaves. 
and tendrils, for example, may represent either leaves or 
branches. The morphological character of bud-scales, on 
the other hand, is usually recognized at once from their 
position, structure, and especially from the various transi- 
tional forms by which they are connected with ordinary 
leaves. Though often puzzling, the morphology of modi- 
fied leaves is always an exceedingly interesting and profit- 
able study. 1 

1 Cf. Gray, Structural Botany, pp. 110-118. 



74 STUDY OF COMMON PLANTS. 



VI. THE FLOWER. 

MATERIAL REQUIRED. 

Flowers of white Trillium, T. grand 'iflorum, Salisb. Other species may 

be used. 
Cultivated Fuchsia. Specimens must be selected that have not become 

double. 
Several pots of cultivated primroses in flower, some specimens with 

long- and others with short-styled flowers. 
Various wild flowers, or cultivated kinds that have not undergone 

modification, may be substituted for the preceding. 

TRILLIUM. T. grandiflorum, Salisb. 

I. Study first the morphological characters. 1 

1. Is the flower complete, that is, are the calyx, corolla, 

stamens, and pistil all present ? 

2. What is the numerical plan as indicated by the num- 

ber of sepals, petals, stamens, and carpels ? 

3. Is the flower regular? 

4. Is coalescence to be observed in the members of any 

whorl ? 

5. Describe in detail each part of the flower, noting 

shape, color, and other features. ' 

II. Make a transverse section of the ovary. Draw it 
sufficiently enlarged to show all the parts clearly. Note 
particularly the form, position, and place of attachment 

1 Read Gray, Lessons, pp. 79-117. 



THE FLOWER. 75 

of the ovules, and make out as much of their structure as 
possible. 

III. Construct a diagram of the flower. 1 

Note. — A correct diagram necessitates a careful study of the relation 
of every part of the flower to every other part. It should be drawn with 
geometrical precision, representing the parts of each whorl so as to show 
their number, arrangement, relation to other whorls, and to some extent 
their union or separation. Properly constructed, such diagrams serve 
an important purpose by facilitating the comparison of the permanent 
morphological features of flowers of the same and different families. 

IV. Ascertain whether the flower manifests any physio- 
logical adaptations. 

1. Is there anything protective in its form, position, or 

structure ? 

2. Enumerate its attractive features. 

3. Is there anything to indicate whether cross- or self- 

fertilization takes place ? 

Note. — A satisfactory answer to this question may require 
more experience than the pupil has yet attained. It involves 
close observation of any peculiarities that seem to favor the visits 
of insects or other agents of fertilization, such as grooves, guiding 
lines, the presence of nectar, and so on. 2 

FUCHSIA. Fuchsia coccinea, etc. 

I. Note carefully all external features, such as 

1. Position of the flower and its direction, erect or 

drooping. Compare with the flower buds. 

2. Color of different whorls. 

3. Union of parts 

a. Of the same whorl. 

b. Of different whorls. 

1 Cf. Gray, Lessons, p. 82, footnote ; also Eichler, Bluthendiagramme. 

2 Cf. Mtiller, Fertilization of Flowers. 



76 STUDY OF COMMON PLANTS. 

4. The extremely long style. 

5. Relative position of anthers and stigma. 

6. Numerical plan. 

II. Make a clean transverse section of the ovary. 
Examine under the dissecting microscope. How many 
carpels are there ? 

III. Draw the section, taking care to represent accu- 
rately 

1. The position of septa and placentae. 

2. Attachment and form of ovules. 

IV. Make an exact longitudinal section and draw it in 
outline. Note particularly 

1. The conspicuous nectary. 

2. Presence or absence of nectar. 

3. The insertion of the filaments and their direction, so 

placed as to bar out unwelcome visitors. 

V.' Measure the length of the calyx tube. Is the nectar 
accessible to bees and similar insects ? 

VI. Construct a diagram. 

VII. Review the whole and describe in detail. 

PRIMROSE. Primula veris, etc. 

I. Study the morphological characters, such as 

1. The numerical plan. 

2. Regularity. 

3. Symmetry. 

4. Coalescence of parts. 

5. Structure of ovary. 

II. Construct a diagram. 



THE FLOWER. 77 

III. Note all protective and attractive arrangements.. 

IV. Compare flowers of a number of different plants 
with regard to the position of the essential organs. Notice 

1. The length and insertion of the stamens. 

2. Length of style. 

3. Form and structure of the stigma. 

4. Any other particulars in which the long- and short- 

styled forms differ. 

V. Make longitudinal sections of the two forms and 
sketch in outline. Read Darwin, Different Forms of 
Flowers on Plants of the Same Species, Chap. I. 

Note.— It will, of course, be understood that an acquaintance with 
many more species will be necessary in order to obtain a general concep- 
tion of the morphology of the flower, and an adequate knowledge of its 
physiological adaptations. Accordingly, similar studies of other flowers 
may be made before proceeding farther, or this may be postponed until 
the families of flowering plants are taken up. In any case the student 
should now read carefully Gray, Lessons, pp. 79-109, or the equivalent 
part of the Structural Botany, by the same author. He should also make 
a constant practice of referring to M tiller, Fertilization of Floioers. 

POLLEN, OVULES, EMBRYO. 

I. Examine with the compound microscope the pollen 
of a number of different plants, such as pine, lily, pump- 
kin, mallow, and others. Compare the grains as to size, 
shape, and surface. Notice whether those disseminated by 
the wind are characterized by different features from those 
that are carried by insects or birds. Draw and describe. 

II. Sow various kinds of pollen in watch glasses con- 
taining sugar solution (3 to 20 per cent). At intervals of 
a day or less transfer a few grains to the glass slide with 
a camers-hair brush and examine microscopically. Some 



78 STUDY OF COMMON PLANTS. 

of them will soon show formation of pollen-tubes. Draw 
them in different stages of development. 1 

III. Cut transverse sections of the ovary of Trillium at 
the time the flower is fading and at subsequent periods. 
Under the compound microscope study the ovules in 
different stages of growth. Notice 

1. The anatropous form of the ovule. 

2. Its two coats distinctly marked at the apex. 

3. The nucellus, or mass of tissue making up the body 

of the ovule. 

4. The micropyle, a canal leading from the apex of the 

ovule to the nucellus. 
Draw and describe. 

IV. Prepare similar sections of the ovary of Fuchsia, 
Begonia, and various other plants, studying carefully, as 
before, the structure of the ovule. Some of these will 
show, lying within the nucellus, the outlines of the embryo- 
sac, a large cell in which the embryo is subsequently 
formed. Clearing with potash solution facilitates the 
observation. Indian-pipe, Monotropa uniflora, L., when 
it can be obtained, is an extremely favorable species for 
the study of the embryo-sac and the structures contained 
in it. 2 

V. Take a flower-bud of shepherd's-purse, Capsella 
Bursa-pastoris, Moench, and under a lens remove the floral 
envelopes. Open the ovary and dissect out the ovules. 
Treat on the slide with dilute potash solution and apply 
light pressure to the cover glass. If a series of younger 

1 For further hints as to culture methods, cf. Strasburger and Hill- 
house, Practical Botany, p. 320 c; Halsted, Bot. Gaz. XII (1887), 
p. 287. 

2 Cf. Strasburger and Hillhouse, I.e., pp. 327-337. 



THE FLOWEK. 79 

and older specimens are prepared in this way, the embryo 
in various stages of development can be satisfactorily 
studied. Make a series of sketches showing as many of 
these stages as practicable. Compare your own figures 
with those of Hanstein. 1 Write a brief account of the 
development of the embryo of this plant as far as you 
have observed it. 

SPECIAL STUDIES. 2 

I. Morphology of stamens. 

II. Morphology of the pistil. 

III. Protection against unbidden guests. 

IV. Dimorphism. 

V. Mechanical devices favoring cross-fertilization. 

VI. Changes in the ovule after fertilization. 

REVIEW AND SUMMARY.^ 

In the preceding study we have found that a flower is 
commonly made up of four distinct whorls, or circles, 
calyx, corolla, stamens, and pistil. The parts p arts f the 
of the calyx are called sepals, those of the cor- flower ' 
olla, petals. The stamens are spoken of collectively as the 
androecium, and the pistil (or pistils) as the gymecium. 
While in most flowers- all the parts are present, there are 

1 Goebel, Outlines of Classification and Special Morphology, p. 397. 

2 Gray, Structural Botany, pp. 215-240, 251-268 ; Kerner, Flowers and 
their Unbidden Guests; Darwin, Different Forms of Flowers on Plants 
of the Same Species; Strasburger and Hillhouse, Practical Botany, pp. 
311-337. 

3 It will probably be better to postpone the review until the flowers of 
a considerable number of families have been carefully studied. After 
this has been done the pupil may profitably devote some little time to the 
resume and references here snven. 



80 STUDY OF COMMON PLANTS. 

many species in which one or more of the whorls are 
absent, and each is subject to more or less modification 
of form and structure. 

Morphologically the flower is to be regarded as a modi- 
fied branch, the members of its different whorls corre- 
its morphol- sponding to so many leaves. The most obvious 
°SJ' reasons for this view are that the flower has the 

position of a branch; that the arrangement of its parts 
follows more or less strictly that of the leaves on the stem ; 
that the anatomy of leaves and* floral structures is essen- 
tially the same ; that transitions from ordinary leaves to 
floral envelopes are of frequent occurrence ; and finally 
that reversions of parts of the flower to a more primitive or 
leaf -like form often take place. 

It is convenient, and at the same time in accordance 
with the views now held regarding the actual evolution of 
Typical plant life, to take some such flower as that of 

flower. the Trillium as a pattern or " typical" flower 

with which to compare others. The Trillium, as we have 
seen, has three distinct green sepals, three petals, two 
whorls of stamens of three each, and a pistil composed of 
three parts, each part called a carpel. We may character- 
ize our pattern flower, then, as having all the parts present, 
these parts distinct from each other, of the same form and 
size in each whorl, and presenting throughout the same 
numerical plan, most frequently three or five. In other 
words, it exhibits completeness, distinctness of parts, regu- 
larity, and symmetry. 1 

The flowers of most plants differ in one or more respects 
from such a typical flower as has been described. Never- 

1 The flower of Trillium departs slightly from the ideal typical flower 
in the coalescence of the three carpels to form the compound ovary. Cf. 
Gray, Structural Botany, pp. 176-178. 



THE FLOWER. 81 

theless a comparison of the flower of a given species as we 
actually find it, is, as a rule, readily made with 

J . . Modifications. 

the assumed type, and this comparison is a 
necessary part of the morphological study of any flower. 
In carrying out such a study it is found that flowers 
may vary from the type in any one (or in more than one) 
of its characteristic features. In the first place, 

CJoSjIbscgilps 

members of the same whorl, instead of being 
separate, may be more or less completely united. The 
calyx of the primrose, the bell-shaped corolla of the cam- 
panula, the united filaments of various members of the 
pea family, and the compound ovary of the lily, are 
familiar examples. Coalescence of parts is held by bota- 
nists to indicate a higher development than has been 
attained by flowers in which the parts remain free. 

A still further step in the same direction is seen in the 
union of contiguous parts of different circles. Thus the 
flower of the Fuchsia has the calyx-tube so 

-. . t , , . . (, Adnation, 

united with the ovary as to make it appear as it 
inserted on its summit, and both petals and stamens are 
inserted on the calyx, the filaments showing very plainly 
their union with the calyx-tube. The various degrees of 
adnation furnish important characters that are constantly 
employed in descriptive botany. 1 

Again, while the typical flower is regular, having all the 
parts of a given whorl alike in size and shape, the flowers 
of the more highly developed species, as a rule, 
show marked irregularity. The spurred corolla 
of the violet, and the curiously irregular flowers of the 
sweet pea, salvia, and snapdragon are striking cases. It is 
believed that these are descendants of much simpler forms 



Cf. Gray, Structural Botany, pp. 182-184. 



82 STUDY OF COMMON PLANTS. 

that in the course of an indefinite period of time have 
gradually taken on shapes manifestly correlated with the 
visits of insects or other agents by which pollen is carried 
from one flower to another. 

Many flowers have undergone the suppression of one or 
more parts. In some cases a whole whorl is wanting, as 
in the anemone, which is destitute of a corolla ; 
or several whorls may be lacking, as in the wil- 
lows, the flowers of which are reduced to a single whorl. 
Frequently, however, a part of a whorl only is wanting, 
and in such cases it often happens that a rudiment, or 
trace, of the missing parts remains to indicate a former 
condition. In the common toad-flax, for example, there are 
four perfect stamens and a trace of the fifth ; some of the 
mints now have but two stamens, although five was the 
original number ; and many plants, as the lupine and its 
allies, otherwise on the plan of five, have the ovary reduced 
to a single carpel. 

The symmetry of the flower is interfered with, not only 
by the suppression, but also by the multiplication of parts, 
Mnltiplica- so that it not infrequently happens that the 
tion. original plan, in some one whorl at least, is no 

longer recognizable. The very numerous stamens of the 
cacti will serve as an illustration. 

The changes described are of great interest as indicating 
actual steps in the developmental history of flowers. They 
help us to see, if not fully yet in part, how such extraor- 
dinary structures as those of a milkweed flower or an 
orchid have come to be what they are. 1 

1 Lack of space renders it necessary to refer the student to a much 
more extended discussion of the subject than can here be undertaken. 
Cf. Gray, Structural Botany, pp. 179-209, which has been followed in 
the main in the brief resume just given. 



THE FLOWER. 83 

As already intimated, the parts of the flower exhibit 
the same general structure as that of the leaf, structure and 
but with modifications corresponding to the ^notions pf 

1 ° the several 

special functions that each part fulfills. parts. 

The calyx and corolla are protective, serving to guard 
the parts within from frost and rain and the intrusion of 
unwelcome visitors. They are also attractive, pi or al envel- 
particularly the corolla, which is usually col- °P es - 
ored so as to attract bees and other color-loving insects. 
They form, too, a part of the mechanism, often very pecu- 
liar and interesting, by which pollination is effected. 

The stamens are usually far more modified than the 
floral envelopes. The thickened anther, corresponding to 
the blade of the leaf, produces pollen, the active „ 

... . Stamens^ 

agent of fertilization. The pollen consists of 
rounded cells, the walls of which are variously thickened, 
frequently beset with spines, and, in some instances, 
winged, thus facilitating their conveyance by insects or by 
the wind. The cell contents are protoplasm, with one or 
more nuclei, and a considerable quantity of food material, 
such as starch, oil, and sugar. 

The pistil is simple or compound according as it is made 
up of one or more than one carpellary leaf. 1 The ovules, 
which afterwards become the seeds, originate as 
cellular outgrowths from the margins of the 
carpel. An ovule, when fully formed, consists of a cen- 
tral mass of cells, called the nucellus, around which one, 
or commonly two, protective coats are formed, and within 
which a cell, called the embryo-sac, arises. It is in the 
embryo-sac that the young embryo is developed. An 
opening between the coats, called the micropyle, leads 
down to the nucellus. The parts as described at once 

1 Cf . Gray, Structural Botany, p. 260 et seq. 



84 STUDY OF COMMON PLANTS. 

recall the seed, which is simply a fertilized and matured 
ovule. 

When pollen-grains have been brought by any agency 

to the moist and receptive stigma of a flower of the same 

species, they begin after a short interval to ger- 

Fertilization. , T ,. ,, , -, 

minate. In germination pollen-tubes are pro- 
duced, which rapidly elongate, growing through the loose 
tissue of the stigma and downwards through the style until 
they enter the ovary. Here they find their way to the 
ovules, which they enter, one pollen-tube going to each 
ovule and pushing its way through the micropyle, until its 
end comes in contact with the nucellus and finally with 
the embryo-sac. A portion of the contents of the pollen- 
tube, including nuclear material, now passes into the 
embryo-sac and unites with a cell in it, called the oosphere. 
The oosphere now takes on a cell-membrane, increases in 
size, undergoes division, and, as a result of still further 
division and growth, produces the embryo. Other cells 
are formed in the embryo-sac which rapidly multiply and 
become the endosperm, a tissue often absorbed afterwards 
by the growing embryo prior to germination. Meantime 
the embryo-sac becomes many times its former size, while 
the nucellus is crowded to the walls of the ovule and is 
commonly absorbed, but sometimes remains as the peri- 
sperm. The coats of the ovule are extended to keep up 
with this increase in size, the testa takes on its character- 
istic hard and usually colored condition, a further store of 
food is deposited around or in the growing embryo, and 
with the completion of these various processes the ovule 
has become a mature seed. 

The changes just described, together with some others 
that chiefly affect the ovary, take place whether pollen 
from the same flower or from another flower of the same 



THE FLOWER. 85 

species is applied to the stigma; but it has been proved 
that, as a general rule, there are great advan- 
tages in having the pollen brought from another 
flower. 1 Accordingly, while self-fertilization is possible in 
most plants, various arrangements exist by which cross- 
fertilization is favored. 

A number of external agents serve as efficient means of 
pollination. The wind carries the light pollen of pine and 
other trees to great distances, sometimes even External 
hundreds of miles, insects of many different agents. 
kinds are actively engaged in carrying pollen from one 
flower to another, and humming birds visit a considerable 
number of species. In comparatively few cases pollen is 
conveyed to the stigma by the agency of water. 

Flowers themselves show many remarkable adaptations 
that favor cross-fertilization. The most important of these, 
as discussed at length by Darwin and other Adaptations 
writers, are the following: of flowers, 

1. Diclinism, or the separation of stamens and pistils. 
These are borne in different flowers, either on the same 
plant, as in the hazel, oak, etc., or on different individuals, 
as in the willows and poplars. In some families, as the 
maples, both conditions prevail. Plants with staminate 
and pistillate flowers on the same individual are said to 
be monoecious, those in which the separated flowers are 
on different individuals are dioecious, and those in which 
either condition exists together with the production of 
some perfect flowers are called polygamous. Of those in 
which the separation is most complete, namely, perfectly 
dioecious species, Darwin says, " About the origin of such 

1 Cf . Darwin, Cross- and Self-fertilization in the Vegetable Kingdom ; 
* Miiller, Fertilization of Flowers. 



86 STUDY OF COMMON PLANTS. 

plants nothing is known." * This arrangement practically 
necessitates cross-fertilization. 

2. Dichogamy, or the maturing of stamens before or 
after the period of receptivity of the stigma. When the 
stamens shed their pollen before the stigma is receptive, 
the dichogamy is proterandrous ; if, on the other hand, the 
stigma is receptive before the pollen is shed, it is proter- 
ogynous. The former condition is far more common than 
the latter. 2 

3. Prepotency of pollen from other flowers. It has 
been found by experiment that pollen from another indi- 
vidual is often decidedly prepotent over that produced by 
the same flower. This is best shown by placing its own 
pollen on the stigma of a flower, and after some hours 
applying pollen of a different colored variety of the same 
species. The plants raised from seeds of flowers thus 
fertilized show by the color of their flowers whether 
crossing has taken place. Darwin found in a number of 
cases that pollen of another individual was prepotent after 
twenty-three or twenty-four hours. 3 

4. Heteromorphism. A considerable number of species 
produce flowers of different forms. In various species of 
Primula and Houstonia, certain individuals have long sta- 
mens and short styles, while others have long styles and 
short stamens. Such flowers are said to be dimorphic, white 
those of loosestrife, Lythrum Salicaria, L., which have 
stamens and styles of three different lengths, are trimor- 
phic. Both conditions involve the same principle and 
favor cross-fertilization in a remarkable way. 4 

1 Different Forms of Flowers on Plants of the Same Species, p. 278. 

2 Cf . Gray, Structural Botany, p. 219, et seq. 

3 Cross- and Self-fertilization, pp. 395, 396. 

4 Cf. Darwin, Different Forms of Flowers on Plants of the Same 
Species. 



THE FLOWER. 87 

5. Special mechanisms. Such peculiarly shaped flowers 
as those of the lupine, sage, lady's-slipper, milkweed, and 
many other plants exhibit special contrivances, often in 
the form of an exquisitely arranged mechanism, by which 
the flower is adapted to some particular visitor or class of 
visitors, through whose agency it is fertilized. These are 
described at length in various works, and we shall have 
occasion to study some of them in detail as we take up 
different families of plants. 1 

1 The student is given distinctly to understand that the foregoing 
account is necessarily incomplete, and must be supplemented by careful 
and intelligent reading of the references given, if even a fairly complete 
comprehension of the subject is to be attained. It is by no means the 
part of these exercises, with their brief summaries, to cover the subject 
of botany, but to shovj the beginner how to go to work. 



88 STUDY OF COMMON PLANTS. 



VII. FRUITS. 

MATERIAL REQUIRED. 

Mature fruits of sugar maple. Pods of common locust. 

Capsules of opium poppy and of Linaria vulgaris, Mill. 

Fruits of climbing bitter-sweet, Celastrus scandens, L. Cranberries. 

A miscellaneous collection of fruits from the market and elsewhere. 
Among the most easily procurable are the following : Peanut, 
acorn, common plantain, coriander, colocynth, milkweed, black 
pepper, juniper berries, raisins, sumac "berries," rose hip, rig, 
date, banana, star anise, cardamom, cocoanut, apple, plum, mul- 
berry, catalpa, spiraea, evening primrose, and mullein. 

COMMON LOCUST. Robinia Pseudacacia, L. 

I. Taking dry, unopened specimens, note all the ex- 
ternal features, as form, surface, color, and texture. Are 
there any remains of floral structures ? 

II. Open the pod and draw in outline the inner surface 
of one of the halves, showing the position, attachment, 
and form of the seeds. Locate the funiculus and micropyle, 
and indicate their position by letters and dotted lines. 

III. Describe the structure and mode of dehiscence of 
the fruit and classify it. How many carpels are there ? 

POPPY. Papaver somniferum, L. 
I. With uninjured commercial specimens note 

1. The general external characters. 

2. The peculiar stigma. Count the number of divisions. 

3. Mode of dehiscence. 



FRUITS. 89 

II. Make a transverse section and examine the internal 
structure. Ascertain 

1. Where the seeds are attached. 

2. Number and position of the placentae. 

3. Number of carpels. 

SUGAR MAPLE. Acer saccharinum, Wang. 

I. Taking dried specimens, gathered the preceding fall, 
notice 

1. The form of the wings. 

2. Their size as compared with the rest of the fruit. 

3. The lightness and strength of the whole structure. 

What do you infer as to the mode of dissemi- 
nation ? 

II. Make an outline sketch of one of the two halves, 
mericarps, into which the fruit separates. 

III. Soak some of the fruits in water, and after an 
hour notice what changes have taken place. With a 
sharp knife or scalpel remove the pericarp. How does its 
outer part differ from the inner in texture ? Has the seed 
become wet? Describe the means of protection of the 
embryo. 

IV. Taking a mericarp that has soaked a longer time, 
or better, one that has lain on the moist ground from 
the time of its fall, remove the pericarp so as to expose 
the seed in its natural position. Next remove carefully the 
seed-coats and examine the embryo. Observe the way it 
is folded together and the form of the radicle and coty- 
ledons. 

V. Classify the fruit. 1 

1 Cf. Goebel, Outlines of Classification and Special Morphology, p. 
428 ; Gray, Structural Botany, Chap. VII. 



90 STUDY OF COMMON PLANTS. 

BUTTER- AND-EGGS. Linaria vulgaris, Mill. 

I. Place some of the dry capsules in water and watch 
them for a few minutes. Observe and record any changes 
that take place. 

II. Ascertain the following facts : 

1. Number of carpels. 

2. Position of placentae. 

3. Mode of dehiscence. 

CLIMBING BITTER-SWEET. Celastrus scandens, L. 

I. Examine the dry fruits, noting the number, shape, 
and position of the reflexed valves. 

II. Compare specimens that have been soaked in water 
an hour or more and note differences. 

III. Ascertain the number of seeds and describe them. 
They are surrounded by a brightly colored aril. 1 

IV. Classify the fruit and describe the mode of 
dehiscence. 

CRANBERRY. Vaccinium macrocarpon, Ait. 

I. Note critically the external features, including the 
presence or absence of floral envelopes. Can you deter- 
mine by inspection of the fruit whether the ovary should 
be described as superior or inferior ? 

II. Prepare transverse and longitudinal sections. De- 
termine 

1. The number of carpels. 

2. Position and direction of seeds. Draw and describe. 

1 Cf. Gray, Structural Botany, pp. 308, 309. 



FRUITS. 91 



CLASSIFICATION OF FRUITS. 

After a thorough study of a few such fruits as the fore- 
going, examine and classify a large number of easily pro- 
curable sorts, selected so as to secure as great a variety as 
possible. See list given above. Careful attention should 
be given at the same time to their morphology. Endeavor 
to ascertain in each case how many carpels there are, and 
what modifications the parts forming the fruit have under- 
gone. It is desirable to adopt some one classification and 
adhere to it. That of Gray is, on the whole, the most 
satisfactory. 

SPECIAL STUDIES. 1 

I. Projection of seeds. 

II. Arrangements for burying seeds. 

III. Colors of fruits. 

IV. Relationships indicated by fruits. 

V. Variation as seen in cultivated fruits. 
VI. Minute anatomy of the cherry. 

VII. Development of the apple or some other common 
fruit. 

This last may be made an extremely interesting and 
profitable study. Beginning with the flower of the apple, 
cherry, or any of the common fruits, watch day by day the 
changes that take place, keeping a full record of them . 
until the fruit is formed. 

1 Botanical Gazette, Vol. VII (1882), pp. 125, 137 ; Vol. XII (1887), 
p. 225 ; Lubbock, Flowers, Fruits, and Leaves, Chap. Ill ; Wallace, Dar- 
winism, pp. 305-308 ; Darwin, Animals and Plants under Domestication, 
Vol. I, Chap. XI ; Strasburger and Hillhouse, Practical Botany, p. 
347 et seq. 



92 STUDY OF COMMON PLANTS. 



REVIEW AND SUMMARY. 

After the process of fertilization has taken place, re- 
markable changes occur aside from those of the ovule 
Development already described. The corolla withers, and 
of the fruit. the ovary increases in size, finally becoming the 
fruit, which in ordinary cases is to be thought of simply as 
the ripened ovary. In some species, however, the calyx- 
tube forms a part of the fruit, and still other exceptional 
forms of developmental history occur. The wall of the 
ovary, which becomes the pericarp, generally changes in 
texture, becoming firm and leathery as in the bean, or 
fleshy as in the cucumber, or partly fleshy and partly bony 
as in the cherry, and so on. The pericarp often shows 
three fairly distinct layers corresponding to the upper and 
lower epidermis and intervening parenchyma of the car- 
pellary leaf, the outer layer being known as the exocarp, 
the middle, mesocarp, and the inner, endocarp. Thus, in 
the peach, the skin is the exocarp, the fleshy part the 
mesocarp, and the stone the endocarp. In the pod of a 
bean or pea, the correspondence between the parts of the 
pericarp and those of the carpellary leaf is still more 
manifest. In many other fruits the changes that have 
occurred render this relation less easily observed, and are 
frequently still more fundamental in character. In some 
cases in which the ovary is composed of several carpels, 
only one develops, the rest becoming abortive ; in others 
the ovary becomes divided by one or more septa, which 
give the fruit the appearance of having arisen from a com- 
pound pistil with more than the actual number of carpels. 
These and other important features of the developmental 
history of fruits are best understood by a careful com- 
parison of their structure in different stages of growth 
from the pistil to the mature condition. 



FRUITS. 93 

Many of the peculiarities just referred to find their expla- 
nation in physiological adaptations, chiefly those connected 
with protection and the dissemination of seeds, physiological 
Attention has already been directed to these in adaptations. 
our study of seeds, but they may now be briefly noticed 
with more direct reference to the fruit. Fleshy fruits, par- 
ticularly if brightly colored, are attractive to animals, and 
are carried away by them in great numbers, often to very 
remote places. One has only to recall the habits of birds 
in distributing seeds of cherries, strawberries, and many 
other fruits, to realize the importance of these common and 
familiar but nicely adjusted relations. Other fruits, such 
as nuts of various kinds, though less attractive externally, 
are carried away by squirrels and other animals for the 
sake of the abundant food stored up in them. Still other 
fruits, such as the samara of the hop-tree and maple, have 
the pericarp greatly modified in adaptation to dissemina- 
tion by the wind, and a considerable number of dehiscent 
fruits exhibit mechanical arrangements by which their 
seeds are forcibly thrown to a considerable distance. Fre- 
quently, too, the structure of the fruit is manifestly 
adapted to secure the protection of the seed. The thick 
and bitter outer covering of the walnut and its extremely 
hard shell, the rind of the orange with its pungent, 
aromatic oil, the extraordinarily multiplied and thickened 
coverings of the cocoanut, and other arrangements of simi- 
lar character, are so many means of protection against 
attacks of animals, the penetration of water and fungous 
germs, and injury from other destructive agents. 

In systematic botany it becomes necessary, for the sake 
of intelligible description, to employ some one of the 
various classifications of fruits. At the same time, it must 
be understood that such classifications are more or less 



94 STUDY OF COMMON PLANTS. 

artificial, and that their value is rather that of convenience 
than as an expression of relationship. Nevertheless it is 
Classification, the case many times that in a given group of 

Stodgy P lants a certain kind of fruit prevails, not in- 
fruits. frequently to the exclusion of all other kinds. 

Thus the p6po is the fruit of the gourd family, the ache- 
nium of the composites, and so on, so that by means of the 
fruit alone it is often possible to determine the relation- 
ship of the plant from which it came. Accordingly the 
student is advised to familiarize himself with the various 
kinds of fruits by a careful study and classification of such 
a collection as that of the list in this exercise, and in his 
subsequent study of special groups of plants to observe 
how far the kind of fruit is characteristic. Such a mode of 
procedure will give interest and meaning to what other- 
wise is likely to be nothing more than a bete noire to the 
beginner. 

In closing our study of fruits we come back again to the 
seed, with which we started, and it must already have oc- 
Cycle of de- curred to those who are in the habit of stopping 
flowering* ° *° think, that the same plant appears at differ- 
plants. ent periods of its life under widely different 

forms. The seed represents the plant in its period of rest, 
but it is as truly the plant in this state as in its period of 
highest activity. We may even hold, perhaps more accu- 
rately, that a part of the seed — the embryo — strictly rep- 
resents the entire plant, the parts around the embryo being 
merely protective or food-supplying accessories that belong 
in reality to the preceding generation. 1 We have found it 
best to study parts of many different species in order to 

1 The theory of the alternation of generations and the details of 
the reproductive process cannot well be discussed until the student is 
acquainted with flowerless plants. 



FRUITS. 95 

obtain a general conception of the structure and cycle, of 
development of flowering plants, but if we were to take a. 
single seed, and watch its germination and every detail of 
its subsequent life and growth, we should find its develop- 
mental history a connected synopsis of what we have 
learned from so many sources. This may be stated briefly 
as follows : In the spermaphytes, or higher plants, the 
embryo arises from a single cell, the oosphere, contained 
in the embryo-sac. The embryo has all the essential vege- 
tative parts of the mature plant, and in germination these 
are unfolded, finally developing into root, stem, and leaf. 
Certain buds of the plant in this later stage of its develop- 
ment become ordinary branches, while others undergo ex- 
traordinary modifications and become reproductive branches 
or flowers. In due course of time the oosphere is formed 
in the embryo-sac of the various ovules, and after fertiliza- 
tion the same history is repeated in a subsequent genera- 
tion. Later on in our work we shall see that plants lower 
in the scale of life exhibit similar, though not identical, 
phases of developmental history. Before proceeding to 
these, however, we have first to study certain relationships 
of the higher plants among themselves. 



96 STUDY OF COMMON PLANTS. 



VIII. SEAWEEDS AND THEIR ALLIES. ALGJ5. 

MATERIAL REQUIRED. 

Green alga? gathered in a fresh condition from different places. 
Pains should be taken to secure the coarser, branching sorts, 
common in running water, the fine, silky kinds that grow abun- 
dantly in stagnant water, and the dull green felt that forms 
on the damp ground and in pots in conservatories. 

Note to the Teacher. — The arrangement of families and higher 
groups in the following pages is believed to indicate, as well as a lineal 
arrangement can, their natural succession, and is that adopted by modern 
botanical writers. In most preparatory schools, however, certainly in 
those not fully equipped for microscopic work, the best results will be 
attained by following a somewhat different order. After studying the 
organs of flowering plants, it will be found advantageous to pass at once 
to the Coniferse, then to the early flowering families of phanerogams, 
taking them in the order that is most convenient, which will be deter- 
mined chiefly by time of flowering and abundance of material. As a rule, 
the cryptogams should be studied later, although in schools provided with 
a full laboratory outfit the order followed in the book may be the best. 

No attempt is made to treat all families alike. The aim is simply to 
help the student in every case to ascertain existing facts and their mean- 
ing. Observation should constantly be directed to the differences and 
resemblances by which various degrees of relationship are determined. 
The exercises on the Coniferse and Ranunculacese will serve to indicate 
the prominence that may properly be given to this idea, which forms the 
basis of vegetable morphology. On the other hand, observations of 
distribution and physiological adaptations, too much neglected hitherto, 
should receive their full share of attention. It is essential that careful 
descriptions of the plants examined should be written, and that these 
should be accompanied by sketches. The number of these will vary 
according to circumstances and the judgment of the teacher, but they 
are by no means to be omitted. 



SEAWEEDS AND THEIR ALLIES. 97 

SPIROGYRA. S. longata, quinina, etc. 

General Characters. 

The soft, green material called " pond scum," growing 
on the surface of still water, is usually made up largely 
of Spirogyra, not infrequently several species together. 
Notice 

I. The color, varying according to conditions, so that 
specimens from different places, or gathered at different 
times of year, may present a wide range of shades. 

II. The delicate and slippery feeling, reminding one of 
silk when taken between the fingers. 

III. The remarkable difference in size of the filaments 
when examined with a hand lens, or even with the naked 
eye, if specimens of extreme sizes are compared. 

Microscopic Structure. 

Mount in water and examine with the compound micro- 
scope. 

I. Observe that each filament is composed of a single 
row of cells. Follow one of the filaments to the end. 
Are the cells composing it of uniform diameter? Of 
uniform length ? How does the terminal cell differ from 
the others? 

II. Study critically the cell structure. 

1. Focus slowly and compare one cell with another 

until you are satisfied as to their geometrical form. 
Are they " rectangular " or cylindrical ? 

2. Separate the cell-contents from the cell-membrane 

by applying a plasmolyzing agent. Two per cent 



98 STUDY OF COMMON PLANTS. 

salt solution is suitable for this purpose. Watch 
the process of plasmolysis (contraction of the proto- 
plasm and its separation from the cell-membrane). 
Sketch one or two of the cells showing the cell- 
membrane in its place and the contracted proto- 
plasmic contents. 

3. Preparing a fresh slide, so as to have the cells in 

their natural condition, study the cell-contents. 
How many green bands, chlorophyll bodies, are 
there in each cell ? Change the focus slowly, and 
follow a band from one end of the cell to the 
other. What is its shape? Is its edge even or 
irregular? Notice the rounded, highly refractive 
bodies, pyrenoids, contained in it. 

4. Treat with iodine solution, and ascertain whether 

starch occurs in the cells. If so, does it stand 
in any relation to the pyrenoids ? 

5. Look for a nucleus. This is sometimes brought out 

very plainly by the action of iodine. In some 
species it may be seen with perfect clearness with- 
out any treatment. Compare different specimens 
until you know definitely 

a. The position of the nucleus in the cell. 

b. Its shape. 

c. Whether it is connected in any way with other 

parts of the protoplasmic contents. This is a 
very interesting point, difficult to determine in 
some species, but very obvious in others. 

d. Its structure. A nucleolus will readily be found. 

(The finer details of structure require special 
methods not provided for in this course.) 



SEAWEEDS AND THEIR ALLIES. 99 

III. Draw one of the cells with great care large enough 
to show its complete structure. This will require close 
attention to details. Repeat, if necessary, .until you are 
satisfied that your drawing represents truthfully a Spiro- 
gyra cell. 

Describe fully what you have seen so far. 

Xote. — Possibly some things have escaped notice. The septa between 
adjacent cells differ widely in different species. There are still other 
points not likely to be observed except by comparing different forms. 

Reproduction. 

Spirogyra is reproduced sexually by zygospores and non- 
sexually by cell-division. 

I. By zygospores. These may be found in the summer 
time in specimens that look faded or discolored. They 
are not to be looked for in bright green material. 

1. Observe the marked contrast presented by the conju- 

gating filaments to those in the vegetative condition. 
The filaments occur in pairs, one with empty cells, 
the other containing in each of its cells a large, 
commonly oval zygospore. 

2. Notice the structure of the zygospore, with its heavy 

wall and dense contents. 

3. Compare different specimens, and try to make out the 

way in which the zygospores have been produced. 
Notice the connecting-tube by which the cells of 
the empty filament are connected with those of the 
one containing zygospores. See if there are any 
cases in which it contains protoplasm. Look for 
specimens in which instead of a complete tube there 
are protuberances from the opposite cells of the 



100 STUDY OF COMMON PLANTS. 

two filaments. If the material is favorable, you 
will be able by continuing such a comparison to 
observe for yourself the successive stages in the 
development of the zygospores. 1 

II. By cell-division. The nucleus undergoes a remark- 
able series of changes, ending in its separating into two 
new nuclei and the formation of a septum between them. 
In this way a cell becomes divided into two " daughter 
cells " which after attaining their full development divide 
in the same way, the process continuing through a series of 
generations. 2 

Spirogyra is one of the most abundant and widely 
distributed of the green algae. It is always to be had, and 
is one of the most satisfactory plants with which to begin 
the study of the plant celh Zygnema, recognized by its 
stellate chlorophyll bodies, and Mesocarpus, in which a flat 
plate takes the place of a spiral band, are both often found 
with it. All of these, particularly Spirog3^ra and Meso- 
carpus, are capable of almost unlimited use in the demon- 
stration of fundamental facts of vegetable physiology. 
The student will do well to read carefully what is said 
of Spirogyra in the laboratory manuals, and consult the 
references in Arthur, Barnes, and Coulter's Plant Dissec- 
tion, and the recent periodical literature. 

1 Cf. Strasburger, Practical Botany, p. 247 ; Sachs, Physiology of 
Plants, pp. 727, 728. 

2 For details of the process, including nuclear changes, see Strasburger' s 
admirable monograph, Ueber Kern- und ZelUheilung. Jena, 1888. 



SEAWEEDS AND THEIR ALLIES. 101 

VAUCHERIA. V. sessilis, Vauch. 
General Characters. 

Examine with a good hand lens the specimens that 
have been gathered, some from fresh water, others from 
moist soil in greenhouses. Notice 

I. The coarsely filamentous appearance, and the matting 
together to form a thick felt, when growing on the soil in 
flower-pots. 

II. The color. Compare with the bright green of some 
of the finely filamentous scfrts growing in water. 

Microscopic Structure. 

Mount some of the filaments and examine with the 
compound microscope. Observe 

I. The very large size of the cells, a filament, as a rule, 
consisting of a single cell. Try to find the end of one. 
Ascertain whether branches are formed. 

II. The thick cell-wall. Run two per cent salt solution 
under the cover glass, and see if the wall becomes more 
plainly defined. 

III. The cell-contents. These present considerable dif- 
ferences, depending on the age of the plant, and the con- 
ditions under which it grew. Good specimens show in 
the thicker protoplasm next to the cell-wall 

1. Chlorophyll bodies. Observe their shape. 

2. Drops of oil. Apply iodine solution, and determine 

whether starch also is present. 

3. Nuclei. These require special treatment to be brought 

out satisfactorily. 1 

1 Cf. Bower and Vines, Practical Botany, II, p. 76. 



102 STUDY OF COMMON PLANTS. 

Reproduction. 

Vaucheria is reproduced by oospores and also by swarm- 
spores. 1 

I. By oospores. These are easily obtained from speci- 
mens growing on damp earth, and may be satisfactorily 
studied both in living and alcoholic material. Using first 
the low power of the compound microscope, observe 

1. The organs of reproduction generally growing close 

together. 

a. The cylindrical antheridium. 

b. The obliquely oval oogonia, commonly two with 

each antheridium. Draw. 

2. The structure of both antheridium and oogonium. 

Examine this more in detail, using the high power, 
and, if practicable, having fresh material. 

a. Early stages of development may be found. If 

these are met with, make a series of sketches, 
showing both oogonia and antheridia at dif- 
ferent periods. 

b. The process of fertilization should be observed, if 

possible. It will probably involve the outlay 
of considerable time, yet there are few plants 
in which the process can be more satisfactorily 
followed. It is even more striking in CEdogo- 
nium, a plant closely related to Vaucheria, on 
account of the large size of the antherozoids. 2 

II. By swarm-spores. These cannot always be had 
when wanted, but are unusually large, and on account of 

1 For other forms of vegetative reproduction, cf. Goebel, Outlines of 
Classification and Special Morphology, p. 32. 

2 For an account of the process and further directions, cf. Strasburger, 
Practical Botany, pp. 252-254. 



s 



SEAWEEDS AND THEIR ALLIES. 103 

their peculiarities are worth taking pains to secure. Stras- 
burger recommends x that vigorous specimens of Vaucheria, 
growing in running water, be obtained the day before, 
placed in shallow vessels, and fresh water poured over 
them. The swarm-spores are formed the following morn- 
ing, and, on account of their large size, both their structure 
and development are readily observed. 

No further special directions will be needed beyond 
those in the manuals referred to, which should be care- 
fully read. As complete a study as possible should be 
made of this plant, since it stands as a representative of 
those algae in which the sexual reproduction has proceeded 
a step farther than in Spirogyra, male and female cells 
being distinctly differentiated. Many of these are also 
reproduced by swarm-spores. These two modes of repro- 
duction are so common that we expect, as a general rule, 
to find the algae reproducing themselves both sexually and 
non-sexually, a fact that continually presents itself in 
studying other groups of plants, but not often in quite so 
striking a way as here. The non-sexual process is a means 
of rapid reproduction ; sexual reproduction, on the other 
hand, commonly results, in the lower plants at least, in the 
formation of a resting-spore by which £he plant is carried 
through various vicissitudes and dangers, and in which 
by a mingling of the male and female elements in the 
process of fertilization, certain other advantages, not yet 
fully understood, are attained. 

The brown and red algae grow in salt water in nearly all 
cases, and are seaweeds properly so called. They present 
many forms no less interesting than the green algae, but as 
they will not be accessible to the great majority of those 

1 Practical Botany, p. 250. See also Bower and Vines, Practical 
Botany, II, pp. 78-80. 



104 STUDY OF COMMON PLANTS. 

who are likely to use this book their study has not been 
introduced. The various text-books and manuals give the 
necessary help for beginning their study. 1 

1 No provision is made in this work for the study of fungi, not because 
they are unimportant, but because it is better on the whole that the 
student should complete his preparatory course with the definite under- 
standing that he knows nothing whatever about this vast and hetero- 
geneous group. Their introduction, moreover, would break the natural 
succession that the beginner especially should keep continually in view. 



MOSSES AND LIVERWORTS, 105 



IX. MOSSES AND LIVERWORTS. MUSCINE^. 

MATERIAL REQUIRED. 

A collection of common mosses of different genera, e.g. Bryum, 
Climacium, Milium, Polytrichum, Cylindrothecium, Sphagnum, 
and others. AVith care in selecting, and by gathering material 
at different times, some specimens will be obtained in fruit, 
others in the vegetative condition, and still others with arche- 
gonia and antheridia. 

A similar collection of liverworts, including representatives of the 
genera Conocephalus, Lunularia, Riccia, Porella, etc. 

MOSSES. Musci. 

General Characters. 

Without selecting one species for exclusive study, com- 
pare the different kinds of mosses in the collection that 
has been made, and ascertain what general characters they 
have in common. Notice 

I. Their choice of locality. By what does it appear 
to be determined ? Are the habits of the different species 
alike in this respect? 

II. Whether they grow separately or in tufts. 

III. The differentiation of vegetative organs. Is there 
a plain distinction of root, stem, and leaf? If so, is it 
equally marked in the different species ? 

IV. Differences of size, color, and other specific char- 
acters. 



106 STUDY OF COMMON PLANTS. 

V. The fructification, — when fully developed a very 
conspicuous part of the plant. 

Rliizoids. 

I. Examine the different species with reference to the 
occurrence of roots. They are found to have the form 
of hair-like bodies, root-hairs, or rliizoids. Where do they 
arise ? Are they limited to any one part of the plant ? 

II. Remove some of the rhizoids, mount in the usual 
way, and examine under the compound microscope. Pre- 
pare several slides, taking the root-hairs from different 
species, and from different parts of the same plant for 
comparison. 

1. Notice first the color, mode of branching, and other 

external features. 

2. Study more closely the minute structure, observing 

the form of the cells composing the rhizoids, the 
character of their contents, and position of the 
septa. 1 
3,. Notice whether the younger cells of the rhizoids 
differ from the older ones, and if so how. Also 
whether exposure to different conditions, as a 
greater or less amount of light, has any effect on 
the character of the cells or their contents. 

Stem. 

I. Compare the stems of the different mosses, and observe 
their differences of size and habit, contrasting the erect, 
rigid stem of Climacium with the delicate, spreading 
branches of Mnium, the minute forms of Barbula with 
the coarse Polytrichum, and so on. 

1 Cf. Sachs, Physiology of Plants, p. 30. 



MOSSES AND LIVERWORTS. 107 

II. Cut thin transverse sections of the stems of two 
or three different species, and study them under the com- 
pound microscope. Beginning with the outside, notice 

1. The epidermis, consisting of a single layer of periph- 

eral cells. Underneath this, in some of the 
species, are similar, thick-walled cells, the whole 
forming a cylindrical band of mechanical tissue. 

2. The cortex, consisting of rounded cells, often con- 

taining starch and oil. 

3. The axial cylinder, an extremely simple form of fibro- 

vascuiar bundle, occupying the center of the stem, 
and made up of much narrower elements than 
those composing the cortex. Longitudinal sec- 
tions show that these are also much more elongated 
than the cortical cells are. Observe also whether 
they differ from the latter in the color of their 
walls and the character of their contents. 

Eeaf. 

I. Examine next the ordinary foliage leaves of the 

different species, observing 

1. Their differences of size, form, and other external 

features. 

2. Their relation to the stem. Are they stalked or 

sessile? Is their arrangement on the stem alike 
in the different species ? 

3. The structure of an individual leaf, as far as this 

can be observed under a good lens. Notice par- 
ticularly the margins and midrib. 

II. Study fresh and well-developed leaves, such as those 
of new shoots of Mnium, with the compound microscope. 
The cellular structure will be found beautifully distinct, 



108 STUDY OF COMMON PLANTS. 

the cells containing large and clearly defined chlorophyll 
bodies. Notice their position in the cells ; does it appear 
to be constant? 

A little attention will show that the leaf is not a simple 
plate of cells throughout. Examine the midrib and com- 
pare with the axial cylinder of the stem. 

III. Look for other kinds of leaves, scale leaves, of 
frequent occurrence, especially on the lower part of the 
stem, and perichsetial leaves, forming a rosette, usually at 
the apex of fruiting stems. 1 

Fructification. 

I. Taking any of the mosses in the collection that aTe 
in fruit — several species if possible — observe 

1. The slender stalk, seta, on which is borne 

2. The capsule, containing spores. 

Compare the capsules of different species as to size, 
form, color, and other features. 

II. Make a thorough study of the parts composing the 
capsule, using the compound microscope when needed. 

1. The calyptra, commonly a thin membrane covering 

the apical part of the capsule ; rarely, as in 
Polytrichum, a thick hairy cap. Notice the form, 
differing in different genera. 

2. The operculum, in most genera a conical lid, fitting 

closely to the end of the capsule, but thrown off 
when the latter is fully ripe, thus permitting the 
scattering of the spores. 

3. Lightly covered by the operculum when it is in 

place, but showing conspicuously when it is re- 

1 For further suggestions cf. Arthur, Barnes, and Coulter, Plant Dissec- 
tion, p. 84 et seq. 



MOSSES AND LIVERWORTS. 109 

moved, the peristome, or circle of teeth surround- 
ing the opening of the capsule. The peristome 
presents a widely different appearance in the 
different genera, and its structure requires careful 
study. It consists of four, eight, sixteen, thirty- 
two, or sixty-four teeth, plain, or variously cut and 
ribbed, and often very hygroscopic. In a few 
genera the peristome is wanting. 

4. Within the capsule, the spores filling a cylindrical 

space which surrounds a central mass of tissue 
called the columella. 

5. In some mosses, besides the parts already named, 

there are to be observed the epiphragm, a thin, 
membranaceous structure, stretching across the 
mouth of the capsule ; and at the base of the 
capsule a swelling called the apophysis. 

Note. — The structure of the capsule should be studied iu detail 
in a number of different mosses, and descriptions accompanied 
by careful drawings should be written. The peristome, especially, 
is very characteristic and furnishes important features for the sys- 
tematic study of the group. 

Protonema. 

If ripe spores are sown on moist soil, or on a compact 
clump of moss, and kept under a bell-jar at the temperature 
of an ordinary living room, the early stages of develop- 
ment of the protonema are easily observed. The spore 
swells and pushes out a papilla which elongates into a 
tubular cell. This increases in length, becomes septate, and 
branches are formed. 

The later stages of development may be followed out 
with the same material ; but there are some advantages in 
obtaining vigorous specimens by the simple expedient of 
turning a clump of moss bottom side up, and keeping it in 



110 STUDY OF COMMON PLANTS. 

a moist atmosphere for a week or two. By this means the 
relation of rhizoids and protonema is made clear. It is 
seen that they are the same thing, the filamentous growth 
taking the appearance and structure of protonema or 
rhizoids according to the conditions under which it grows. 
It is also seen that the protonema may originate from 
other parts of the plant, as well as from the spore. 

On the protonema, whether it has its origin in the spore, 
or from some other part of the plant, buds arise, from which 
new plants are formed. 

Archegonia and Antheridia. 

Among the specimens, if these have been gathered at dif- 
ferent times of year, some will be likely to show " flowering 
heads," most frequently terminating the stem, and sur- 
rounded by a more or less conspicuous rosette of leaves, 
the perichsetium. The antheridia and archegonia may 
occur together in the same " flower," or in separate flow- 
ers, on the same or on different individuals. 

The whole structure is best studied by means of longi- 
tudinal sections, which are easily made with a razor, after 
a little practice, without any previous preparation of the 
specimen. Examining such sections under the microscope, 
if we chance to have selected a male specimen we shall 
find antheridia in great numbers growing at the apex of 
the axis, and with them slender, filamentous bodies, para- 
physes, while outside of both is the circle of perichaetial 
leaves. The antheridia are sacs, usually oblong in shape, 
with a wall consisting of a single layer of cells, the interior 
being composed of the mother cells of the antherozoids. 
The latter are ciliated, protoplasmic bodies, closely resem- 
bling those of the ferns. In the examination of a female 
specimen the paraphyses are seen as before, but archegonia 



MOSSES AND LIVERWORTS. Ill 

take the place of antheridia. A fully formed archegonium 
is a flask-shaped body with an elongated neck, and an 
enlarged ventral portion, within which is the oosphere. 

Fertilization takes place by the mingling of the substance 
of an antherozoid with that of the oosphere, after the 
antherozoid has forced it way down through the long canal 
of the neck. The fertilized oosphere, now called the 
oospore, becomes septate, and by still further cell-division 
and growth the capsule with its seta, spores, and various 
parts already described, is formed. 

With suitable material and sufficient time the student 
can readily verify most of the facts here given. 

Cycle of Development. 

It will be observed that in the mosses alternation of 
generations takes place. The sporophyte, or non-sexual 
generation, begins with the formation of the oospore and 
closes with the spore, while the oophyte, or sexual genera- 
tion, begins with the germination of the spore, and includes 
both protonema and leafy plant. 

Note. — It is important that this should be perfectly clear. The 
student must see for himself the various stages of development of the 
mosses as far as this is practicable. He may now consult the various 
text-books and manuals, particularly those of Goebel, Arthur, Barnes, 
and Coulter, Bower and Vines, and the references given by them. See 
further on this subject under Ferns. 

The peat mosses, Sphagnaceae, are easily obtained in 
many parts of the country, and afford an opportunity for 
extended and profitable comparative study. Their habits, 
structure of the vegetative organs, and fructification, all 
present interesting points of difference from the true 
mosses. 



112 STUDY OF COMMON PLANTS. 



LIVERWORTS . Hepaticce. 

The liverworts are closely allied to the mosses, their 
cycle of development being essentially identical with that 
of the latter group. Accordingly our work will be re- 
stricted to a comparison of the general characters of some 
of the most easily procurable liverworts. Representatives 
of the genera named at the beginning of this section are 
widely distributed and easily obtained through a con- 
siderable part of the year. Lunularia is of almost uni- 
versal occurrence in greenhouses, and while seldom if ever 
found in fruit, almost always has gemmae in different 
stages of development. Conocephalus is common and 
abundant in moist, shady places. The floating species of 
Riccia have a wide range, as do also some of the species 
of Porella. These and other genera will furnish a full 
supply of material for comparative study. 

The student is advised to proceed with his preliminary 
observations as he did with the mosses, comparing a num- 
ber of different kinds, instead of confining his attention 
to a single species. Differences of habit between these 
and the mosses, the bilateral and dorsi-ventral frond of 
the liverworts, their texture and anatomical structure, and 
peculiarities of fructification should all be noted. If the 
mosses have already been studied as directed, there will 
be little difficulty, with suitable material and the help of 
the various manuals, in obtaining a corresponding general 
view of the structure and habits of the liverworts. 

Many interesting subjects for more extended investi- 
gation present themselves ; among them the following 
are suggested as 



MOSSES AND LIVEliWOUTS. 113 



SPECIAL STUDIES. 

I. Development of the gemmae. Lunularia offers ex- 
cellent and abundant material for this, and its 
gemmae, on account of their simplicity, are among 
the best objects with which to begin studies of 
developmental history. 

II. Comparison of the anatomy of Conocephalus with 
that of Marchantia. The latter is selected because 
of its being so fully described in the books. For 
the former, Lunularia or some other genus may 
be substituted if more convenient. 

III. Rhizoids of liverworts compared with those of mosses. 

IV. Structure of the mature sporocarp in the different 

families of liverworts. 

V. Comparison of the archegonia and antheridia of 
liverworts and mosses. 

VI. Alternation of generations as seen in mosses and 
liverworts compared with the ferns and other 
vascular cryptogams. This will naturally be post- 
poned until after the study of the latter groups. 
It will be found that in the ferns the oophytic 
generation is reduced to a green prothallium, and 
in the club-mosses and their allies a still further 
reduction takes place. 

VII. Origin of the calyptra of mosses. 



114 STUDY OF COMMON PLANTS. 



X. FERNS. FILICINE^H. 

MATERIAL REQUIRED. 

Shield-fern, Aspidium cristatum, Swartz, gathered in summer when the 

fructification is fully developed. 
Similar specimens of maidenhair, Adiantum pedatum, L., brake, Pteris 

aquilina, L., spleen wort, Asplenium Filix-fcemina, Bernh. 
Representatives of other genera of ferns that are procurable, such as 

Cystopteris, Woodwardia, Osmunda, Dicksonia, etc. 

SHIELD-FERN. Aspidium cristatum, Swartz. 

General Characters. 

I. Record first what you have observed as to the habits 
and habitat of the plant. Does it grow in moist or dry 
ground? in shady places or in the open? How do its 
habits compare with those of other ferns, as regards choice 
of soil and surroundings ? 1 

II. Notice the parts of the plant. 

1. The underground stem, from which arise 

2. Large, compound leaves, fronds, and 

3. Roots. Observe their origin, form, and structure. 

Leaf. 

The leaf is the most characteristic part of the fern, and is 
to be studied in detail. Notice 

1 Cf. Underwood, Our Native Ferns and their Allies. 



FERNS. 115 

I. The leaf-stalk, stipe, with many thin, brown scales. 
Are these persistent or deciduous ? 

II. The outline of the frond and the form of its main 
divisions, pinnae. 

III. How the pinnae are divided. Compare the descrip- 
tion of this species in Gray's Manual, p. 688. 

IV. The venation. Select one of the pinnse in which 
this is well defined, and draw it carefully in outline, tak- 
ing pains to represent accurately the exact position of the 
veins, tracing them to the end of their ultimate divisions. 

Fructification, 

I. The conspicuous bodies on the under side of the 
pinnae are the sori, or fruit-dots. Observe 

1. Their position. Are they situated on the back or 

alongside of the veinlet ? 

2. The thin, scale-like covering, indusium, protecting 

the spores. 

II. Taking specimens nearly or quite mature, remove 
the indusium, and with a good lens look at the spore-cases, 
sporangia. Mount in water in the usual way, and examine 
under a low power of the compound microscope. Observe 

1. The general form and structure of the sporangium, — 

a flattened sac, the walls of which are composed of 
distinct cells. 

2. The annulus, a row of thick-walled cells, forming a 

continuation of the stalk. Does the annulus ex- 
tend completely around the sporangium ? 

III. Examine the sporangia under a high power, observ- 
ing them in different positions. Compare different speci- 
mens and draw a perfect one. 



116 STUDY OF COMMON PLANTS. 

IV. Using material that has been kept in alcohol, mount 
some of the sporangia in water as before, and examine 
microscopically. Run a drop of glycerine under the cover 
glass and notice the result. Repeat the experiment until 
you are satisfied as to the way the spores are discharged 
from the sporangium. 

Note. — This is by no means an easy problem. Notice where the 
sporangium ruptures, the form of the cells composing the annulus, and 
the changes they undergo with its change of position. Try the use of 
different media, such as strong salt solution, etc. Compare the sporangia 
of different ferns, and see whether all have the same structure and behave 
alike. 

V. Under the highest power, study the form and struct- 
ure of the spores. Draw one or more of them. 

VI. Taking almost any sorus except the oldest ones, 
study the development of the sporangium by carefully 
comparing the structure at different ages. A series of 
drawings should be made illustrating as many stages as 
possible. 1 

Prothallium. 

If fern spores are sown on soil, or on pieces of decayed 
wood, and are kept in a moist atmosphere, they will germi- 
nate, and give rise to a structure known as the prothallium. 

I. The early stages of development of the prothallium 
are easily observed by examining the spores at intervals 
during the first few days after they have been sown. 
Microscopic examination shows that the spore swells, the 
outer coat, exospore, ruptures, and the inner coat, endospore, 
protrudes in the form of a papilla, which rapidly elongates 
into a delicate, tube-like structure, the first root-hair. The 

1 Cf. Goebel, Outlines of Classification and Special Morphology, p. 217 
et seq. 



FERNS. 117 

spore itself elongates at the same time and becomes sep- 
tate, the septa at first arising at right angles to its 
direction of growth. By further growth, and a series of 
divisions in different directions, the mature pro thallium 
is finally produced. While the prothallium is in the 
early, or filamentous stage of its development, the form 
and contents of its cells and other structural details are 
easily observed. Full descriptions, accompanied by care- 
ful drawings, should be made. 1 

II. The mature prothallium may be raised successfully 
by taking care of the specimens that have been started 
as directed above ; but since they require weeks, or even 
months, to attain their full development, it is more con- 
venient to obtain prothallia from conservatories where 
ferns are cultivated. In the pots containing ferns, or on 
the surface of the moist earth near by, one can frequently 
find excellent specimens. They are generally heart-shaped, 
a few millimeters to a centimeter in diameter, of a delicate 
green color, and so much like small liverworts as some- 
times to deceive experienced collectors. 

An uninjured specimen that has been carefully washed, so 
as to remove the adherent particles of earth, shows under 
the microscope a deep anterior depression, sinus, and back 
of this a thickened portion of the prothallium, sometimes 
called the cushion. The latter is several layers of cells in 
thickness, while the parts nearer the margin are but one 
layer thick. Rhizoids in great numbers arise from the 
lower surface. The growing point is at the base of the 
depression. The arrangement of the cells at this point 
indicates their order of development, which is readily 

1 For a model cf. Campbell, Development of the Ostrich Fern. 
Memoirs, Boston Soc. Nat. Hist., Vol. IV, No. II (1887). 



118 STUDY OF COMMON PLANTS. 

made out if younger specimens of different ages are com- 
pared. 

After the points named have been observed, drawings of 
the mature prothallium should be made and compared with 
those of earlier stages. If the material is suitable for the 
purpose, intermediate stages of development also may be 
studied. 

III. On the lower side of the mature prothallium arche- 
gonia and antheridia are produced. These are organs of 
reproduction, corresponding in function to the "essential 
organs " of flowering plants. The archegonia are usually 
situated near the sinus. They are flask-shaped bodies, the 
lower portion of which is sunk in the tissue of the 
prothallium, while the neck projects above the surface. 
The neck consists of a wall made up of four longitudinal 
rows of cells, surrounding a single row of canal-cells which 
lead down to the obsphere. The latter is the cell from 
which, after fertilization, the embryo, i.e. the young frond, 
arises. 

The antheridia are, as a rule, more remote from the 
sinus, and present the appearance of small, hemispherical 
protuberances, consisting of a wall one layer of cells thick, 
which encloses the mother-cells of the anther ozoids. The 
latter are minute, ciliated, protoplasmic bodies, and are the 
active agents of fertilization. They are best observed by 
placing in water on a slide prothallia that have been kept 
rather dry for some time. After the water has been 
absorbed by the antheridium the latter ruptures, and the 
antherozoids in great numbers are seen in active motion, 
swarming in the field of the microscope like so many 
animalcules. Under favorable circumstances they have 
been seen to move towards an archegonium and enter 
it, passing down through the canal-cells which have now 



FERNS. 119 

become mucilaginous. The union of an antherozoid with 
the oosphere is necessary in order to the subsequent 
development of the latter. 1 

Developmental History and Minute Anatomy. 2 

The oosphere after fertilization becomes surrounded by a 
cell-membrane, and is now known as the oospore. It is 
afterwards divided into two cells by a septum nearly 
parallel with the axis of the archegonium. This is fol- 
lowed by the formation of two additional septa at right 
angles with the first and with each other, the oospore being 
thus divided into eight parts or octants. Further cell- 
division takes place, and the embryo soon shows a differ- 
entiation into a foot, or absorptive organ, by which it draws 
nutriment from the prothallium, a first root, leaf, and stem. 
The first leaf, root, and foot are temporary structures, all 
of them serving the needs of the plant for a comparatively 
short period. The stem, on the other hand, is of slow 
growth, but is permanent, and finally attains the size and 
structure that it exhibits in the mature plant; roots and 
leaves arise from it, the prothallium finally disappears, and 
the so-called sporophyte takes the place of the preceding or 
oophyte generation. 

1 Only a bare outline is given above. For further details the student 
should consult Strasburger, Practical Botany, pp. 290-296 ; Bennett and 
Murray, Cryptogamic Botany, p. 64 et seq. ; Goebel, Outlines of Classifi- 
cation and Special Morphology, p. 198 et seq., and references given by the 
authors just named. For some of the most recent and valuable contri- 
butions see Campbell, Development of the Ostrich Fern, and various 
papers by the same author in the Botanical Gazette, Annals of Botany, 
and other periodicals. 

2 A practical study of the developmental history of ferns requires more 
time than can possibly be given to it in a preparatory course, and accord- 
ingly it is thought best to omit altogether directions for laboratory work, 
merely giving a resume of the cycle of development as it has been worked 
out by different botanists. Cf. Goebel, I.e., p. 204 et seq. 



120 STUDY OF COMMON PLANTS. 

The alternation of generations just referred to appears 
very clearly in the ferns. The oophyte, or sexual gener- 
ation, includes the stage beginning with the germination 
of the spore and closing with the fertilization of the 
oosphere. The sporophyte, or non-sexual generation, be- 
gins with the formation of the oospore and closes with the 
mature spore. The prothallium is, therefore, the charac- 
teristic feature of the oophytic generation, and the leafy 
plant, in this case the "fern," of the sporophytic generation. 1 

Full instruction for the study of the minute anatomy of 
ferns is given in a number of accessible manuals, and need 
not be repeated here. A quite full and satisfactory ac- 
count of Pteris is given by Sedgwick and Wilson in their 
General Biology ; Adiantum is well treated by Arthur, 
Barnes, and Coulter in the Plant Dissection ; and Bower 
and Vines give sufficient help for a thorough microscopic 
study of Aspidium. It appears to the writer better, if the 
time is limited, to undertake complete examination of 
only one part, preferably the stem, since the leaf repeats 
in its general structure much of what has already been 
seen in the flowering plants. In studying the stem, most 
of the time should be given to the fibro-vascular bundle, 
including a comparison of its structure with that of the 
bundle of Indian corn and the apple tree. The investiga- 
tion may well be extended to various other plants ; but its 
success will depend on the preparation and judgment of 
the teacher, and the previous training of the student. On 
the whole, a comprehensive study of the fibro-vascular 

1 So much depends on a correct conception of the alternation of gen- 
erations, that the teacher is advised to review, illustrate, and, in short, use 
all means to make it clear. It stands as a prominent developmental 
character, common to all the groups of plants from mosses to phanero- 
gams. Cf. Sachs, History of Botany, pp. 200, 201. 



FERNS. 121 

bundle hardly falls within the scope of an elementary 
course. 

RELATIONSHIP. 

A careful comparative study of a number of prominent 
genera of ferns should be made. Those named above are 
widely distributed, and, in general, easily procurable. For 
this part of the work, dried specimens are nearly or quite 
as satisfactory as fresh ones. The comparison, while in- 
cluding a study of external characters, should be directed 
primarily to the fructification, which presents the really 
distinctive features of the different genera. It is necessary 
in each of the genera studied, to observe particularly the 
form of the sorus and indusium, and the way in which the 
latter is attached to the leaf. If ten or a dozen different 
kinds of ferns are studied in this way, with accompanying 
drawings and descriptions, the student will have learned 
from his own observation the salient characters of the 
ferns as a group, the marks that distinguish the more 
prominent genera, and the features by which the species 
belonging to them are recognized. 1 

The ferns include three thousand or more species, vary- 
ing widely among themselves in habits and external feat- 
ures. With leaves of extraordinary variety and beauty ; 
their texture delicate or coriaceous, or extremely thin and 
translucent, as in the filmy ferns ; of various habits, creep- 
ing, climbing, erect, or tree-like ; growing in every quarter 
of the globe, and yet exhibiting marked preferences of soil 
and surroundings ; a dominant group in earlier geological 
time, and still holding a manifest supremacy among the 
higher cryptogams, — they present themselves as one of the 
most varied and attractive, and at the same time most easily 

1 For further hints see Underwood, Our Native Ferns and their Allies. 



122 STUDY OF COMMON PLANTS. 

studied groups of plants. They are of special interest as 
representatives of the higher fiowerless plants, the vascular 
cryptogams, since they share with them certain develop- 
mental features that are wanting or are imperfectly seen 
in phanerogams. The alternation of generations is far more 
easily recognized here than in flowering plants, since both 
generations are characterized by structures of considerable 
size. The oophyte, or sexual generation, presents us with 
the prothallium, which is a relatively conspicuous, leaf-like 
body, bearing archegonia and antheridia, structures that do 
not occur in the same form in phanerogams. 1 The system- 
atic literature is extended and rather expensive. Eaton's 
Ferns of North America is the best for this country, and 
the works of Hooker and Baker give the most help on 
foreign species ; but with Gray's Manual or Underwood's 
little book, the student will be able to identify without 
difficulty the ferns indigenous to the region where he lives, 
and this is suggested to him as an interesting and instruc- 
tive piece of systematic work. 

1 On the homologies of these organs as they exist in higher plants cf . 
Bennett and Mnrray, Cryptogamic Botany, p. 11 et seq. ; Goebel, Out- 
lines of Classification and Special Morphology ; Macmillan, Metaspermce 
of the Minnesota Valley, and recent periodical literature. 



HORSETAILS. 123 



XI. HORSETAILS. EQUISETINE^. 

MATERIAL REQUIRED. 

Common horsetail, Equisetum arvense, L. The fertile fronds must be 
gathered in the spring when the spores are mature. These are 
preferably examined fresh, but may be preserved in alcohol. 
Sterile fronds in the early stages of development may be gathered 
at the same time, but fully formed ones will have to be obtained 
later in the season, unless they are pressed or put up in alcohol 
the preceding year. Underground stems, with fronds attached, 
should be collected. 

Other species of the same genus, such as the scouring-rush, Equisetum 
hiemale, L., and others. 

COMMON HORSETAIL. Equisetum arvense, L. 
General Characters. 

I. Note first the habits of the plant, the places in which 
it grows best, and the time of year when it appears above 
ground. 

II. Compare the two forms that arise from the same 
rootstock, the fertile and sterile fronds, noting points of 
likeness and difference. 

III. Examine the underground stem, observing its 
peculiarities of form, size, and structure as compared with 
the aerial stems. 

Fertile Frond. 

I. Examine the fertile frond throughout, and describe 
in detail its characteristic features. Notice 



124 STUDY OF COMMON PLANTS. 

1. The succession of nodes and internodes. Are there 

any branches ? 

2. The whorls of modified leaves arising at the nodes. 

How many leaves are there at each node ? Are 
they separate or united ? Do they differ in either 
texture or color from the stem ? If so, how ? 

3. Surface, form, and structure of the stem. Cut a 

transverse section of an internode and examine 
under a dissecting microscope. Is it solid or 
hollow? Notice the openings, lacunae, and their 
number and position. Are these constant in differ- 
ent specimens? Is there any mechanical advantage 
in such a disposition of material ? 
Make an outline sketch of the section, using, if 
necessary, a higher magnifying power. 

II. Study next the spike terminating the stem and 
bearing the fructification. It will be seen that it is a 
modified portion of the stem, showing a succession of nodes 
and internodes, and exhibiting more or less perfectly the 
same structural features as other parts of the stem. 

1. With a pair of fine forceps remove one or more of 

the leaves, here called scales, and examine them 
carefully. Their study will be facilitated by 
making transverse and longitudinal sections of the 
spike, so as to expose the scales more fully. Are 
they stalked or sessile ? Draw one in outline. 

2. Examine under a lens the spore-cases, sporangia, 

borne on the under surface of each scale. How 
many are there ? What is their shape ? Make an 
outline sketch. 

III. Remove carefully one of the sporangia, mount in 
water, and examine with the compound microscope. Be 



HORSETAILS. 125 

sure to have a well-formed and uninjured specimen. 
Observe the peculiar structure of the cells that compose 
the sporangium wall. Ascertain, if you can, how the 
sporangium opens. 1 Draw carefully a few of the cells, 
using the high power. 

IV. Examine the spores under the high power of the 
compound microscope, mounting some of them in water 
and others dry. How do the dry ones differ from those in 
water? Breathe gently on them, and see if any changes 
take place. Draw one or more of the spores with their 
slender, hygroscopic appendages, elaters. 

V. Sow some of the spores in water and others on moist 
soil, and at intervals examine with the microscope. Germi- 
nation of the spores and the early stages of development 
of the prothallium are easily observed, and should be figured 
and described. 

Sterile Frond. 

I. Examine specimens of the sterile frond throughout, 
comparing them in detail with the fertile ones. How do 
they differ from the latter in size, color, texture, formation 
of branches, and structure on transverse section? Is 
there a " division of labor"? If so, point out what you 
conceive to be the most important function of the fertile 
frond; of the sterile frond. 

II. Study the fibro-vascular bundles, and compare with 
those of the fertile frond. Verify the details of structure 
as given by Goebel, Outlines of Classification and Special 
Morphology, pp. 270-272. 

1 CA. Newcombe, Spore-dissemination of Equisetmn, Bot. Gaz., Vol. 
XIII (1888), p. 173. 



126 STUDY OF COMMON PLANTS. 



RELATIONSHIP. 



With the species already studied compare others of the 
same genus, such as Equisetum hiemale, L., E, Umosum, L., 
etc. Do these species show the same general structure ? 
Do they present the same differentiation into fertile and 
sterile fronds ? 

Comparison with still other species of the single genus now 
composing this family 1 shows that the Equisetinese possess 
very marked and characteristic features by which they are 
distinguished from all other families of plants. At the 
same time their close relationship with the ferns is evident 
when their developmental history is followed out. If the 
spores of the common horsetail are sown as directed above, 
the development of the prothallium, including the forma- 
tion of archegonia and antheridia, can be observed in detail 
in the course of a few weeks, and affords a most instructive 
study. 2 If this study is carried far enough to include the 
formation of the embryo and growth of the young plant, it 
is seen that the cycle of development is essentially identical 
with that of the ferns. 

1 The horsetails are remnants of a family which once flourished luxuri- 
antly, reaching its highest development in the Carboniferous period, when 
there were several genera, including a number of tree-like species. 

2 Cf. Campbell, Male Prothallium of the Common Horsetail, Amer. 
Nat., 1883, p. 10. 



CLUB-MOSSES AND THEIR ALLIES. 127 



XII. CLUB-MOSSES AND THEIR ALLIES. 
LYCOPODINE^E. 

MATERIAL REQUIRED. 

Fresh specimens of Selaginella from the conservatory. A number of 
species are common in cultivation, and any of them may be used. 

Club-moss, Lycopodium clavatum, L., with spore-bearing spikes. Simi- 
lar specimens of other species of the same genus, e.g. L. lucidu- 
lum, Michx., L. complanatum, L., etc. 

Any other vascular cryptogams that are procurable, as Marsilia or 
Isoetes. 

SELAGINELLA. S. stolonifera, denticulata, etc. 

General Characters. 

I. Record your observations of the plant as a whole. 
Where did it grow, and under what conditions ? Point out 
any peculiarities of form, texture, or habit, by which it 
would readily be distinguished from ferns. 

II. Examine carefully the mode of branching. Draw a 
diagram to represent it. Is it dichotomous or monopodial ? x 
The plant is said to be bilateral and dorsi-ventral ; show 
how this is true. How do you distinguish between the 
dorsal and ventral aspect of the plant ? 2 

III. Describe the form and arrangement of the leaves. 
Are they all alike ? How many rows are there ? 

IV. On well-developed specimens, slender, root-like 
organs, rhizophores, are to be found. Notice where these 

1 Cf. Bower and Vines, Practical Botany, I, p. 162. 

2 Cf . Strasburger, Practical Botany, p. 296. 



128 STUDY OF COMMON PLANTS. 

arise, whether from the lower (ventral), or upper (dorsal) 
side of the stem. Where their ends come in contact with 
the soil, roots are produced. Observe their peculiar mode 
of branching, unusual for roots. 

Fructification . 

The fertile branches are not particularly conspicuous and 
may be overlooked ; they are readily recognized, however, 
by their rigid, erect habit and quadrangular outline, in 
contrast with the flattened and spreading sterile branches. 

I. Notice the form and arrangement of the leaves. 
How T do they differ from those of other parts of the plant ? 

II. The spore-cases, sporangia, arise singly in the axils 
of the leaves. They are of two kinds, microsporangia in 
the axils of the upper leaves, and macrosporangia, few in 
number, in the axils of the lower leaves of the fertile 
branch. Examine different specimens, under a good lens, 
until you are satisfied as to the position of the two kinds 
of sporangia and their external differences. 

III. With a pair of fine forceps remove the upper part 
of a fertile branch with its microsporangia. Dissect care- 
fully on a slide, and examine with the low power of the 
compound microscope. Compare the sporangia as they lie 
in various positions and notice 

1. The exact relation of the sporangium to the stem 

and leaf,, and whether it is stalked or sessile. 

2. Its form and mode of dehiscence. 

Note. — The cause of the opening of the sporangium may not 
be obvious, but there is no difficulty in finding the line of dehis- 
cence and observing the escape of the spores. 

3. The structure of the sporangium wall. 

4. The spores, set free in great numbers when the spo- 



CLUB-MOSSES AND THEIR ALLIES. 129 

opens. From their small size, as com- 
pared with those produced in the macrosporangia, 
these are called microspores. With the high power, 
observe 
a. The form of the microspores. Are they strictly 

spherical? 
6. Their structure, particularly the spiny exospore 
and granular contents. 

IV. Remove a macrosporangium from the lower part of 
a fertile branch and examine on the slide, using first a 
good lens, and afterwards the compound microscope. Ob- 
serve 

1. The obvious external differences by which this is 

distinguished from the microsporangium. 

2. The number of spores contained in the sporangium. 

From their relatively large size, these are called 
macrospores. 

3. The structure of the macrospores. This is readily 

made out by simply treating with potash solution, 
and dissecting away the hard external coat, as 
recommended by Bower and Vines. 1 After removal 
of the exospore, the smooth, light-colored endo- 
spore is found, and the contents of the spore, chiefly 
oil and aleurone grains, with the mass of cells 
composing the prothallium, are plainly seen. Sec- 
tioning must be resorted to, if these are shown 
accurately in position; but all of them can be 
recognized easily and satisfactorily by following 
the treatment suggested. 

Note. — It is important that these parts should be clearly seen 
and understood. In Selaginella the prothallium is formed before 

1 Practical Botany, I, p. 173. 



130 STUDY OF COMMON PLANTS. 

the spore has left the mother plant, and it is still for some time 
enclosed in the macrospore, which also contains a large amount of 
food materials. The whole structure shows a likeness on the one 
hand to the spores of other vascular cryptogams, and on the other 
to the embryo-sac of flowering plants. 

Developmental History and Minute Anatomy, 

As in the case of the fern, a laboratory study of the 
developmental history requires a special investigation ex- 
tending through some weeks or months. The following 
important features of the cycle of development may be 
mentioned: Selaginella, as well as the ferns and horse- 
tails, is characterized by alternation of the oophyte, or 
sexual generation, with the sporophyte, or non-sexual gen- 
eration. The latter differs widely from that of the ferns, in 
that instead of one kind of spore, giving rise to prothallia 
which bear both antheridia and archegonia, there are two 
kinds, macrospores, or female (archegonia-bearing) spores, 
and microspores, or male (antheridia-bearing) spores, are 
produced, — a distinct foreshadowing of what is seen 
in flowering plants, — the microspores corresponding to 
pollen-grains, and the macrospores to the embryo-sac of 
the ovule. The oophyte, again, as compared with that 
of the ferns, is reduced in size, and all its early stages of 
development are completed within the spore, reminding us 
of similar facts in the developmental history of phanero- 
gams. The prothallium of the microspore, in particular, 
is reduced to the lowest terms, and should be compared 
with the two or more vegetative cells (rudimentary pro- 
thallium) in the pollen-grain of certain gymnosperms. 
The archegonia, produced onty on the prothallium of the 
macrospore, are essentially like those of ferns, though 
somewhat simpler, but after fertilization the first septum 
of the oospore is formed at right angles to the axis 



CLUB-MOSSES AND THEIR ALLIES. 131 

of the archegonium, and the upper of the two cells thus 
formed develops into a suspensor, a structure characteris- 
tic of flowering plants, but occurring in few cryptogams. 

RELATIONSHIP. 

It is desirable that at least the external characters and 
fructification of one or more additional genera of vascular 
cryptogams should be studied in connection with the pre- 
ceding ones ; but specific directions are omitted, partly 
because of uncertainty as to material likely to be procura- 
ble, and partly because it is understood that by this time 
the student should be in a position to make an intelligent 
comparative study of at least the general characters of 
any group to which he has already given special attention. 
Club-mosses are as likely to be available as any of the 
Lycopodinese, since they are pretty widely distributed, 
and besides are extensively used for Christmas decorations. 
As they appear in market in the middle of winter they are 
frequently in fruit. Marsilia and Isoetes are of great 
interest, and when they can be obtained may well claim 
a considerable share of the time given to this group. 
Aside from the manuals and text-books, the references 
given below will be found serviceable to those who under- 
take a further study of the vascular cryptogams. 1 

1 Campbell, Development of Pilularia globalifera, L., Annals of 
Botany, Vol. II, p. 233 ; Contributions to the Life- History of Isoetes, 
Annals of Botany, Vol. V, p. 231 ; On the Prothallium and Embryo of 
Osmunda Claytoniana, L., and 0. cinnamomea, L., Annals of Botany, 
Vol. VI, p. 49; On the Affinities of the Filicinece, Botanical Gazette, 
Vol. XV (1890), p. 1 ; On the Belationships of the Archegoniata, Botani- 
cal Gazette, Vol. XVI (1891), p. 323. Frequent references to other 
important literature are given by the author in the papers cited. 



132 STUDY OF COMMON PLANTS. 



XIII. THE PINE 'FAMILY. CONIFERS. 

MATERIAL REQUIRED. 

Twigs of the following species: White pine, Pinus Strobus, L.; Aus- 
trian pine, Pinus Austriaca, Hcess; Norway spruce, Picea excelsa, 
Lk. ; Hemlock, Tsuga Canadensis, Carr. ; Juniper, Juniperus com- 
munis, L. ; Red cedar, Juniperus Virginiana, L. ; Arbor Vitse, 
Thuja occidentalis, L. 

Mature fruits of the preceding, and flowers, both staminate and pis- 
tillate, as far as these can be procured. 

Substitutions, such as Scotch in place of Austrian pine, may be made 
as occasion requires. 

WHITE AND AUSTRIAN PINE. 

I. Compare branches of the two species as to surface 
markings and other external characters. 

II. Compare the foliage leaves. 

1. How many are produced in a fascicle? Examine 

specimens enough of both species to determine the 
general rule, since exceptions frequently occur. 

2. How do those of the two species differ in length, 

thickness, rigidity, and color? 

3. With a sharp knife make a transverse section of a 

leaf of each kind. Examine with a lens and note 
difference of outline. 

III. Examine next the different sorts of scale-like leaves. 

Notice 

1. Differences of size and texture. 



THE PINE FAMILY. 133 

2. Whether they are deciduous or persistent. Do the 
two species agree in this respect ? 

IV. Study cones of the two species, and note the points 
in which they agree or differ. 

V. Extend the comparison, if practicable, to the stand- 
ing trees, observing their mode of branching and other 
characteristic features. 

VI. Finally, passing in review all the points to which 
attention has been called, summarize your observations in 
a brief written description, taking care to bring out clearly 
the distinctive characteristics of each species. 

NORWAY SPRUCE. HEMLOCK. 

Determine in what respects the Norway spruce differs 
from the pines. Is the arrangement of the branches the same? 
How do the leaves compare in size, form, and mode of inser- 
tion with those of the pines ? Compare the terminal buds. 
Is there anything common to the cones of the two species 
of pines not belonging U> those of the Norway spruce ? 
Do the seeds of the latter differ in any structural par- 
ticular from those of the former ? 

In the same way compare the hemlock with the different 
species already studied, noting arrangement of branches, 
position, form, and size of leaves, peculiarities of terminal 
buds, structure of cones, and other characteristic features. 

JUNIPER AND RED CEDAR. 

I. Compare the two species and note all points of dif- 
ference and resemblance. 

1. What is the form of the leaves of the juniper? 
Number of leaves in a whorl ? How do those of 
the red cedar compare in size, shape, and arrange- 



134 STUDY OF COMMON PLANTS. 

ment with those of the juniper? Are the leaves 
of the red cedar all alike? Do they all exhibit 
the same arrangement? 
2. If the fruits are to be had, study their structure and 

points of resemblance and difference. 
8. If living specimens are accessible, compare the habits 
of the two species. Which assumes the size and 
habits of a tree? Is this difference constant? 
II. Next compare these with the conifers previously 
studied. What characters are common to the juniper 
and red cedar that do not belong to the pine, spruce, 
and hemlock ? 

ARBOR VITiE. 

I. Observe the form of the leaves and their arrange- 
ment on the branches. Are the leaves all alike ? Do 
they exhibit any structural peculiarity not observed in 
those of the other conifers ? 

II. Compare the cones with those of other genera. Is 
the arrangement of the scales flhe same? How does it 
compare with the leaf arrangement ? 

When the pollen of the different species begins to be 
shed in May, compare the structure of the flowers, both 
staminate and pistillate, of as many different conifers as 
can be obtained. 

I. How do the staminate flowers of the hemlock differ 
from those of the Norway spruce? From those of the 
pines? What peculiarities are presented, by those of the 
red cedar ? 

II. Make a similar comparison of the pistillate flowers ? 

III. Of all the species studied which are monoecious? 
Are any of them dioecious ? 



THE PINE FAMILY. 135 

Write » brief summary of the particulars in which all the 
species thus far examined agree. These, with certain 
features that you have not yet observed, constitute the 
family characters of the Coniferae. 

RELATIONSHIP. 

From the preceding study it will be easy to understand 
something of the relationship of plants and the way this is 
determined by botanists. 

1. Plants that are related to each other show a mutual 

resemblance. This may be observed in 

a. External features and habits, including form, direc- 

tion of growth, etc. 

b. Structure. 

c. Reproduction. 

d. Developmental history. 

e. To some extent, physiological peculiarities. But 

in this respect closely related plants often show 
great differences. 

In our study of the conifers we have directed our atten- 
tion chiefly to external features. 

2. Plants exhibit degrees of relationship, those most 

closely related being most alike, while those re- 
motely related are less alike. 

3. Plants that are related as parents and offspring, 

forming a succession of individuals not to be 
distinguished from each other by any constant 
differences, constitute a species. The white pine 
is one species, the Austrian pine another, and 
so on. 

4. Closely related species constitute a genus. Thus the 

various species* of pines together make up the 



136 STUDY OF COMMON PLANTS. 

genus Pinus, and the different species of juniper, 
the genus Juniperus. We have thus far studied 
one or more representatives of each of the genera 
Pinus, Juniperus, Picea, Tsuga, Thuja. 

5. Closely related genera constitute a family. The 

genera just named, with a number of others, make 
up the Coniferae, or Pine family. 

6. Closely related families constitute higher groups, 

sometimes designated as orders, though the usage 
is not uniform. Finally, orders (of flowering 
plants) are grouped together in the great classes 
gymnosperms, monocotyledons, and dicotyledons. 

The relationships here pointed out are those of descent. 
It is believed that just as all individuals of a species are 
descendants of a common ancestor, so all the species of a 
genus and all the genera of a family have a common, 
though remote origin. 

We shall have constant opportunity in our further study 
of plants to become acquainted with specific, generic, and 
family characters. Their recognition is frequently at- 
tended with some difficulty, and in all cases the exercise 
of careful judgment is required. In fact botanical work 
consists very largely in accumulating evidence by which 
degrees of relationship are determined. 



THE GRASS FAMILY. 137 



XIV. THE GRASS FAMILY. GRAMINE^. 1 

MATERIAL REQUIRED. 

Entire plants of cultivated wheat, soon after it has headed out. 

Similar specimens of the following grasses : Chess, Bromus secalinus, L. ; 
Quick-grass, Agropyrum repens, Beauv. ; Orchard-grass, Dactylis 
glomerata, L. ; Fowl meadow-grass, Glyceria nervata. Trim; Barn- 
yard-grass, Panicum Crus-galli, L. ; Indian rice, Zizania aquatica, 
L. ; Bur-grass, Cenchrus tribuloides, L. ; Beard-grass, Andropogon 
furcatus, Muhl. ; Timothy, Phleum pratense, L. ; June grass, Poa 
pratensis, L. 

Some of these can be obtained in a suitable condition for study early 
in -June in the northern States, and at a still earlier date farther 
south ; others are best examined in late summer or autumn. Rye 
may be used instead of wheat, and other substitutions may be 
made if necessary. 

WHEAT. Triticum vulgare, Villars. 
General Characters. 

I. Taking a number of entire and uninjured specimens, 
determine first the relation of the stem and root system. 
Is there anything to show whether more than one culm is 
produced from a grain of wheat ? " By the process of til- 
lering, or multiplication of stems from one root . . . over 
fifteen hundred grains have been obtained from a single 
seed." The beginnings of this process may be observed in 
seedlings of wheat started in the laboratory. 

II. Examine the stem, culm, and note all peculiarities of 

1 The Graminese will be studied to better advantage after some other 
families of monocotyledons, such, for example, as the Liliaceae. 



138 STUDY OF COMMON PLANTS. 

form and structure. Is any mechanical principle involved 
in the disposition of material ? Observe the number and 
position of the nodes (parts of the stem to which the leaves 
are attached). Do they contribute in any way to the 
strength of the structure ? 

Bend the culm through several degrees, after stripping 
off the leaves. Where are the weakest parts ? Is there 
any special protection or support for these parts ? 

Taken as a whole, is the stem satisfactorily constructed to 
sustain the weight of the head and resist the stress of winds? 

Note. — Microscopic examination shows a simple but effective arrange- 
ment of the mechanical elements of the culm, by which great strength is 
secured with a minimum of material. 1 

III. Take up next the relation of leaves and stem. 
How are the leaves attached ? Are their sheaths entire or 
slit? What is the leaf arrangement? 

IV. Note the form and structure of the leaves, and the 
manner in which they twist in drying. 2 

Notice the appendage of the leaf at the angle made by 
the blade and culm. What is it morphologically, and 
what is it called ? 3 

Inflorescence and Flowers. 

I. Notice first the general features of the inflorescence. 
It has the form of a thickened spike, composed of many 
spikelets. The latter are arranged alternately on each side of 
a " zigzag, jointed, channelled rachis." Remove half a dozen 
or more of the lower spikelets to make this more obvious. 

II. Study next the structure of one of the spikelets. 
Each spikelet includes several flowers and is subtended by 

1 Cf. Haberlandt, Physiologische Pflanzenanatomie, p. 114 et seq. 

2 Cf. Beal, Grasses of North America, p. 29 et seq. 

3 Cf. Gray, Structural Botany, p. 106. 



THE GRASS FAMILY. 139 

two glumes. Observe the form and texture of the glumes. 
Are they symmetrical or one-sided ? Is their surface 
smooth or hairy? Are there any longitudinal ribs or 
" nerves''? 

III. Ascertain how many flowers there are in a spikelet. 
Each of the fully developed flowers is subtended by a 
floral glume and a palet. The former, in the bearded vari- 
eties of wheat, bears at its apex a long, barbed awn. 

IV. Compare carefully the floral glume and palet, not- 
ing their differences of form, position, and structure. 

V. Separate the floral glume and palet so as to expose 
the parts of the flower within. Examine flowers of differ- 
ent ages until the essential organs are found in good 
condition. How many stamens are there? How many 
stigmas? Look for some minute, scale-like bodies, lodi- 
cules. How many are there, and where are they placed ? 

VI. Construct a diagram of the flower, showing the 
position of the floral glume, palet, lodicules, stamens, and 
pistil. 1 

VII. Open different flowers of the same head, and con- 
tinue the examination until the relations of anther and 
stigma are ascertained. Does it appear that the flowers of 
wheat are cross- or self-fertilized. 2 

RELATIONSHIP. 

Obtain good specimens of any of the genera named 
above, and compare them with wheat throughout, noting 
all points of difference and agreement. Chess is excellent 

1 Cf. Eichler, Bliithendiagramme, p. 119 et seq. Some interesting sug- 
gestions are given by Allen, Flowers and their Pedigrees, p. 160 et seq. 

2 Cf. Beal, I.e., p. 37 et seq. 



140 STUDY OF COMMON PLANTS. 

to begin with, on account of the simplicity and distinct- 
ness of its floral structures. Many of the other genera 
are likely to prove rather troublesome until the student 
has had some experience. 

After careful comparison of as many different kinds of 
grasses as practicable, summarize your observations in a 
general account of the characters of the Graminese. 

This family includes some four thousand species and is 
of great economical importance, since it furnishes, directly 
or indirectly, by far the larger part of the food of the human 
race. Botanically it presents many points of interest. 
While there are many species of grasses within the tropics, 
they form a characteristic "sod" only in the cooler parts 
of the world. Some depart so widely from the habits of 
those we have studied as to be properly reckoned among 
climbing plants. Although giving evidence of very con- 
siderable modification, the flowers are, with few exceptions, 
destitute of odor and attractive colors, and are either self- 
fertilized or depend for fertilization on the agency of the 
wind. The seeds are disseminated in a variety of ways, 
some passing undigested through the alimentary canal of 
herbivorous animals, others, as Cenchrus, bearing hooked 
or spiny appendages, and still others, as Stipa, provided 
with a twisting awn that attaches itself to the coats of 
animals or buries the grain in the earth. In Tripsacum 
the joints of the spike break apart and are often floated 
away by water, while species of Panicum and Eragrostis 
are blown about by the wind as " tumble-weeds." The 
cultivation of the most important grains is prehistoric and 
their origin uncertain. 1 

1 Cf . De Candolle, Origin of Cultivated Plants, p. 354 et. seq. ; Hackel, 
The True Grasses ; Beal, Grasses of North America. 



THE SEDGE FAMILY. 141 



.XV. THE SEDGE FAMILY. CYPERACE^G. 

The study of this family involves no little difficulty, and its various 
genera present such wide differences that it is impossible to select 
one that maybe taken strictly as a "type." Nevertheless, it is 
desirable that at least the conspicuous and widely distributed 
genus Carex should be familiarly known. 

As a convenient representative, we select one of the most common 
species. 

CAREX. C. hystricina, Muhl. 
General Characters. 

Note the locality and choice of surroundings, the habit 
of growth, whether in clumps or scattered, the height to 
which the plant grows, and general resemblance, if any, to 
other plants already studied. 

Stem and Leaves. 

I. Notice the form and structure of the culm. How 
does it differ from that of wheat and other grasses ? 

II. Note the relation of stem and leaves. In how many 
ranks are the latter disposed ? How do their sheaths differ 
from those of the grasses ? Is there a ligule ? 

III. Describe the leaves as to form and surface. Observe 
their behavior in drying. 

Inflorescence and Flowers. 

I. How many inflorescences are there? Are they sessile 
or stalked ? 



142 STUDY OF COMMON PLANTS. 

II. Beginning with the lowest inflorescence, study care- 
fully the individual flowers. Note first that each flower 
is borne in the axil of a bract or scale. Describe the latter 
as to form, color, and structure. 

III. Each flower is further protected by a sac called the 
perigynium. Examine this, observing critically its form 
and surface, venation, and the long beak terminating above 
in two sharp teeth. 

IV. Open the perigynium and examine the pistillate 
flower. It consists of a single pistil, which in some species 
of Carex has two stigmas with a lenticular ovary, caryopsis, 
while in others the caryopsis is triangular, and the stigmas 
are three in number. Which do you find to be the case in 
this species ? 

V. Taking younger specimens, examine the uppermost 
(staminate) spikes. How do they differ in external 
features from the pistillate ones ? Is each flower sub- 
tended by a scale ? Does it have a perigynium ? How 
many stamens are there ? 

VI. From the observed facts, what do you infer as to 
the mode of fertilization ? 

RELATIONSHIP. 

A number of other species should, if possible, be com- 
pared with the one just studied. Carex lupulina, utricu- 
lata, striata, gracillima, laxiflora, Pennsylvania, rosea, etc., 
are of common occurrence and suitable for such a com- 
parison. The beginner will do well to heed Professor 
Bailey's remark to the effect that this is "an exceedingly 
critical genus, the study of which should be attempted 
only with complete and fully mature specimens." After 



THE SEDGE FAMILY. 143 

becoming familiar with several representatives of the 
genus Carex, some time may be given to a few other 
genera of Cyperacese, as, for example, Cyperus, Eleo- 
charis, Scirpus, and Eriophorum. An intelligent compari- 
son of a limited number of well-developed and well-chosen 
forms will place the student in a position to continue 
his work satisfactorily ; but the study of sedges demands 
clear judgment and unlimited patience, and will never 
prove attractive to any one who is not possessed of 
these qualities. For classification, Gray's Manual, sixth 
edition, will serve a good purpose. Professor L. H. 
Bailey's Types of the Crenus Carex, Memoirs of the Torrey 
Botanical Club, Vol. I, No. I, is the most important con- 
tribution that has yet been made to our knowledge of 
North American species. 



144 STUDY OF COMMON PLANTS. 



XVI. THE ARUM FAMILY. ARACE^E. 

MATERIAL REQUIRED. 

Entire plants of Indian turnip, Ariscema triphyllum, Torr., in flower. 
Similar specimens of skunk-cabbage, Symplocarpus foetidus, Salisb. 
Flowers of cultivated calla; Richardia Africana, Kunth. 
Other plants of this order that are procurable, such as sweet-flag, 
Acorus Calamus, L., and any of the cultivated aroids. 

INDIAN TURNIP. Ariscema triphyllum, Torr. 
General Characters. 

Examine entire specimens in a fresh condition. Note 

I. The thick, rounded, underground stem, corm, more or 
less wrinkled externally. 

II. Long fibrous roots growing out from its upper part. 

III. Above ground, the smooth, cylindrical stem with 
membranaceous, sheath-like leaves below, and one or two 
large, compound, foliage leaves above. Describe the latter 
in detail. 

IV. The peculiar venation, differing from that of a 
majority of monocotyledons. Sketch one of the leaflets in 
outline, and point out the mechanical advantages. 

V. Note the acrid taste due to the mechanical effect of 
the raphides (crystals) on the tongue and throat. 

Inflorescence and Flowers. 

I. The inflorescence is covered by a peculiarly shaped, 
arched spathe. Compare this in a number of specimens, 
and note variations. 



THE ARUM FAMILY. 145 

II. Open a spathe so as to explore the parts within. 
Observe 

1. The elongated, club-shaped, sterile portion of the 

spadix. 

2. The lower, fertile part, on which the naked flowers 

are borne. 

III. Examine the flowers of a number of different 
individuals. It will be seen that, as a rule, some have 
only pistillate flowers and others only staminate ones. 
Notice 

1. The very simple structure of the staminate flowers 

and the mode of dehiscence of their anthers. 

2. The closely packed pistillate flowers, each with a 

sessile, white stigma. Make sections and ascertain 
the structure of the ovary, and the number and 
position of the ovules. 

IV. Ascertain by a further comparison of specimens 
whether this species is strictly dioecious. 

V. If Ariscema Dracontium, Schott., can be obtained, 
compare it throughout with the species just studied, 
noting carefully all points of likeness and difference. 

SKUNK-CABBAGE. Sijmplocarpus foetidus, Salisb. 

General Characters. 

The skunk-cabbage is in flower very early in the season. 
Its striking features at once attract attention. The dis- 
agreeable odor, suggesting its common name, the thick, 
shell-like spathe enclosing the large, rounded spadix, the 
ample leaves, and numerous long, fleshy roots, arising 
from the thickened rootstock, mark this as an exceed- 



146 STUDY OF COMMON PLANTS. 

ingly well-defined species. Record what you have ob- 
served regarding the habitat and duration of the plant, 
and any other characters not mentioned above. Do its 
habits indicate that it is indigenous ? 

Inflorescence and Flowers. 

I. In studying the plant, remove the spathe, observing 
meantime whether any special devices exist for the attrac- 
tion of visitors. 

II. Examine the spadix carefully, comparing it in plants 
of different ages. The flowers are said to be proterogynous. 
Is the statement confirmed by your observation ? 

III. Satisfy yourself by a further comparison of speci- 
mens whether self-fertilization is possible. 1 

IV. Examine the individual flowers, making sections 
for this purpose that will show their structure and rela- 
tion to the axis of inflorescence. Are all the flowers 
perfect? How do the stamens of older flowers differ from 
those less developed ? 

V. Construct a diagram showing the plan of the flower. 

CALLA. Richardia Africana, Kunth. 

Compare the inflorescence and flowers of the cultivated 
calla with those of the preceding species. Note 

I. The color and form of the spathe. 

II. The structure of the flowers. Are they perfect? 
Are there any floral envelopes ? 

III. How do those of the upper part of the spadix com- 
pare with those of the lower portion ? 

1 Cf. Trelease, Am. Nat., September, 1879. 



THE ARUM FAMILY. 147 

A comparative study should be made of such other 
aroids as can be procured, e.g. sweet-flag, water-arum, etc. 
Aside from the peculiarities of their inflorescence, which 
mark them as a unique group, the acrid properties of 
many members of this family constitute a marked feature. 1 

1 Miiller, Fertilization of Flowers, pp. 562-565, should be consulted. 
Some interesting facts and suggestions are given by Allen, Flowers and 
their Pedigrees, pp. 236-266. Certain peculiarities of fruits and seeds 
may be looked for as different genera are examined, such as 

1. The gelatinous outer surface of the fruit of Peltandra. 

2. The seeds, — albuminous in some genera and exalbuminous in 
others. 

3. The embryo, — green in a number of genera. 



148 STUDY OF COMMON PLANTS. 

XVII. THE LILY FAMILY. LILIACE^E. 

MATERIAL REQUIRED. 

Yellow adder's-tongue, Erythronium Americanum, Ker., in flower. 
Representatives of other conspicuous genera of this family, as for 

example : Convallaria, Ornithogalum, Smilacina, Uvularia, Lilium, 

etc. 

Taking any of the plants named above, when in full 
bloom, examine the structure of the flower, studying it 
whorl by whorl, as directed in the case of Trillium, Sec- 
tion VI. 

Comparison of even a few genera of Liliacese is sufficient 
to show very wide differences of external features. At 
the same time the regularity and fixed plan of the flower 
afford constant and distinctive characters by which the 
immediate recognition of the family is assured. The 
student, however, should compare the flowers of a num- 
ber of different species until their morphology is perfectly 
familiar. This is the more important, inasmuch as the 
flower of the Liliacese serves as a type with which to com- 
pare the modified flowers of a number of related families 
of monocotyledons. 

The family includes about sixteen hundred species, in- 
habiting chiefly the temperate and warmer regions of the 
globe. Many of the most pleasing and widely cultivated 
ornamental plants, among them the tulip, lily, hyacinth, 
and lily-of-the-valley, belong to this family. With them 
are also included such medicinal plants as aloe, sarsapa- 



THE LILY FAMILY. 149 

rilla, etc., and, among vegetables, the onion, asparagus, 
and some others. The extraordinary extent to which the 
vegetative organs have been modified, as illustrated by 
the cladophylls of asparagus and Ruscus, indicate a com- 
paratively remote origin, notwithstanding the relative sim- 
plicity of the flowers, some of which, however, as the 
Yucca, exhibit very remarkable relations to insects. 

The student is advised to extend his acquaintance to as 
many genera as possible, and to follow as far as opportunity 
offers, the transitional stages through which it is believed 
that the more highly developed ones have passed. 1 See 
Muller's admirable review of the Liliaceae, Fertilization of 
Flowers, pp. 558, 559, and the papers of Riley and Trelease, 
third and fourth annual reports of the Missouri Botanical 
Garden, 1892 and 1893. 

1 A number of interesting points for comparison will present them- 
selves as the family is studied, e.g. 

1. The nectaries which vary much in different genera. 

2. Bulblets produced in the axils of the leaves of Lilium. 

3. Wide differences of underground stems. Contrast the creeping 
rootstock of Smilacina, Medeola, etc., with the bulb of Lilium and Scilla. 



150 STUDY OF COMMON PLANTS. 



XVIII. AMARYLLIS FAMILY. 
AMARYLLIDACE^E. 

MATERIAL REQUIRED. 

Flowers of the cultivated Amaryllis in various stages of development. 

Specimens should be selected that have just opened, others more 

advanced, and still others that have been open a longer time. In 

addition to these a single entire plant. 
Other representatives of the family that are procurable, such as 

Hypoxis, Galanthus, or Narcissus, in flower. 

I. In what particular does the flower of the Amaryllis 
differ from that of the lily ? From that of the Iris ? 

II. How does the plant as a whole differ from those of 
the Iridacese that yon have studied ? 

III. Compare a number of flowers of Amaryllis, in differ- 
ent stages of development. What arrangements do you 
find for cross-fertilization? To what class of visitors are 
many of the plants of this family adapted ? 1 

IV. Having examined as many plants of the Amarylli- 
clacese as are to be had, enumerate the essential features 
that they possess in common. 

V. Finally point out the characters in which all three 
families, Amaryllidaceee, Iridaceae, and Liliacese, agree. 

The close relationship of these three families of plants is 
obvious upon acquaintance with even a few species. The 

1 Cf. Muller, Fertilization of Floivers, p. 560. 



THE AMARYLLIS FAMILY. 151 

first "differs from the Liliaceae in the inferior ovary," and 
approaches the simple forms of the Iridaceae, which, how- 
ever, are distinguished by having three stamens instead of 
six. 

Note. — Exercises of this kind should be introduced and frequently 
repeated, as soon as the pupil is in possession of a sufficient number of 
observations to make intelligent comparisons. By this means the impor- 
tant fact will become impressed on the mind, that groups of related 
families may be recognized by their common characters, precisely as groups 
of related genera are. 



152 STUDY OF COMMON PLANTS. 



XIX. THE IRIS FAMILY. IRIDACE^. 

MATERIAL REQUIRED. 

Blue flag, Iris versicolor, L., in flower. 
Blue-eyed grass, Sisyrinchium angustifolium, Mill. 
Cultivated Iris, Gladiolus, and Crocus. 

BLUE FLAG. Iris versicolor, L. 
Distribution and General Characters. 

I. Does the plant manifest a decided choice of locality? 
Is there anything to indicate whether it is an indigenous 

species ? 

II. Notice the form and arrangement of the leaves. 
They are described as equitant. When studying other 
species recall this peculiarity, and observe whether it is 
characteristic of the family. How do the bracts that 
subtend the flowers compare with the stem leaves ? 

III. Write a description of the plant as a whole, includ- 
ing rootstock, stem, and leaves. 

Flower. 

I. Study first the morphological characters. 

1. Look over the flower, whorl by whorl, and see 

whether you recognize each part. 

2. Determine the plan. How many divisions of the 

perianth are there ? How many stamens and 
styles ? Does the plan of the flower differ in any 
particular from that of the lily (or Trillium)? 



THE IRIS FAMILY. 153 

3. Study carefully the modifications exhibited by this 
flower, as compared with the lily taken as a type. 
Have any parts been suppressed ? Does adnation 
occur ? What are some of the most striking pecu- 
liarities of form and structure ? 

II. Examine each part in detail with reference to the 
arrangements for cross-fertilization. 

1. Enumerate the attractive features. 

2. Ascertain whether there is a store of nectar, and if so 

whether there are any path-pointers to direct visit- 
ing insects towards it. 

3. Observe particularly the position of stamens and 

stigma. 

a. Position of the anther and its mode of dehiscence. 

b. Location of the stigmatic surface. Examine 

under a good lens. 

"The curved style-branches have at their tip a small 
deltoid crest which turns slightly backward. Under this 
there is a thin shelf, the upper surface of which is covered 
with minute hairs, and is moistened with a sticky secretion. 
This shelf is the true stigma." Verify this description as 
given by Dr. Goodale, Wild Flowers of America, p. 34. 

What do all these peculiarities of structure, color, and 
arrangement suggest? Do you regard self-fertilization as 
possible in this species? If you infer that cross-fertiliza- 
tion takes place, show how this is probably brought about. 1 

BLUE-EYED GRASS. Sisyrinchium angustifoliam, Mill. 

This species is widely distributed, and continues to 
flower for some weeks, so that it can usually be obtained 
for comparison. 

1 Cf. Gray, How Plants Behave, pp. 21, 25 ; Muller, Fertilization of 
Flowers, p. 543 et seq. 



154 STUDY OF COMMON PLANTS. 

I. With entire specimens make a careful study of the 
blue-ej^ed grass, noting all the points in which it agrees 
with the Iris or differs from it. 

1. Compare the essential organs as to number, position, 

and structure. 

2. How does the perianth differ from that of the Iris? 

3. Compare leaves, stem, and roots. 

II. Record concisely the results of your comparative 
study of the two genera, taking care to bring out the 
really essential features that indicate their relationship. 

In like manner compare with the two preceding species 
any other plants of this family that can be procured, 
as the cultivated Gladiolus or Crocus. Some of the latter 
open early in the spring, and the study of the Iridacese 
may begin with them if more convenient. After studying 
as many representatives of the family as practicable, 
summarize your observations in a brief synopsis of the 
characters common to them all. As a subject of special 
investigation, a comparative study of the arrangements for 
fertilization in the Iridacese is suggested. 



THE ORCHIS FAMILY. 155 



XX. THE ORCHIS FAMILY. ORCHIDACE^E. 

MATERIAL REQUIRED. 

Yellow lady's-slipper, Cypripedium pubescens, Willd., and Arethusa, 
Arethusa bulbosa, L., in flower. Other species of Cypripedium may 
be substituted for the former, and Calopogon or Pogonia for the lat- 
ter. If it is impossible to obtain indigenous species, various trop- 
ical orchids can be procured through florists in the larger cities, 
who will deliver them safely at a distance. The expense is of 
small moment compared with what is gained by having a familiar 
acquaintance with at least two or three representatives of a family 
of plants in which mechanical contrivances for securing cross- 
fertilization have been carried to the highest degree of perfection. 

YELLOW LADY'S-SLIPPER. Cypripedium pubescens, Willd. 
Flower. 

Our study will be restricted to the flower, which, though 
greatly modified, has departed from the type less than those 
of other genera, and remains " as a record of a former and 
more simple state" of the great family to which it belongs. 1 

I. Notice first the most conspicuous external features. 

1. The nodding flower, generally single, terminating 

the leafy stem. 

2. The floral envelopes. 

a. Three sepals, of which the upper one is the 
largest, the two lower united into one, but 
showing at the apex a trace of their original 
separation. 

1 Darwin, Fertilization of Orchids, p. 226. 



156 STUDY OF COMMON PLANTS. 

b. The petals, of which the two lateral ones resemble 

the sepals, but are narrower and more or less 

twisted, while the lower 1 is developed into a 

large sac, the lip or labellum. 

3. The essential organs. These have been greatly 

modified, and are united above into an organ 

called the column. Note 

a. The three stamens, the single sterile one forming 
a broadly triangular body, the apex of which 
projects slightly into the opening of the label- 
lum, and the two lateral fertile ones, each 
with a large anther on the under side. 

5. The fleshy stigma, arching under the sterile 
stamen, the stigmatic surface covered with 
minute papillae. This is seen to better advan- 
tage after the removal of the floral envelopes. 

II. Having learned the parts of the flower, endeavor 
next to understand their homologies. Such a study is 
extremely interesting, showing as it does " how curiously 
a flower may be moulded out of many separate organs, — 
how perfect the cohesion of primordially distinct parts 
may become, — how organs may be used for purposes 
widely different from their proper uses, — how other 
organs may be entirely suppressed, or leave mere useless 
emblems of their former existence, — and finally . . . 
how enormous has been the amount of change which these 
flowers have undergone from their parental or typical 
form." 2 

1 "The lip (in the Orchidacese) is really the upper petal, i.e. the one 
next to the axis, but by a twist of the ovary of half a turn it is more com- 
monly directed forward, and brought next to the bract." 

2 Darwin, Z.c, p. 234. 



THE ORCHIS FAMILY. 157 

1. Compare the flower throughout with that of the lily 

(or Trillium) previously studied, endeavoring to 
ascertain the character and extent of its modifi- 
cations. 

a. How does the ovary compare with that of the 

lily as regards adnation of the floral envel- 
opes? 

b. In what parts of the flower has coalescence oc- 

curred ? 

c. Has suppression of any parts taken place ? 

d. Point out the most striking modifications of 
form. 1 

2. Construct a diagram and compare with that of the 

my- 2 

Note. — The student cannot hope to understand all of this at 
once. The distance between the lily and the lady's-slipper is too 
great to be bridged by a single effort of the imagination. Let him 
do his best with the flower itself, then read the references, then lay 
the whole matter aside, and return to it again after other representa- 
tives of the family have been studied. 

III. The striking modifications of the flower of Cypri- 
pedium are correlated with the visits of insects on which 
it is dependent for fertilization. 

1. There are certain peculiarities likely to prove attrac- 

tive to insect visitors. Enumerate these. 

2. Assuming that an insect, a bee for example, is about 

to pass into the interior of the labellum, where 
would it be likely to enter? Would it probably 
pass out by the same opening ? 

3. Examine carefully the structural peculiarities of the 

lip. Find where the tissue is thinnest, and accord- 

1 Cf. Gray, Structural Botany, p. 179 et seq. 

2 Cf. Goodale, Wild Flowers of America, p. 86 ; Darwin, Fertilization 
of Orchids, pp. 234-246. 



158 STUDY OF COMMON PLANTS. 

ingly where the most light is admitted. If the 
insect crawling on the floor of the labellum moves 
towards the part that is best lighted, which direc- 
tion will it take ? Are there any path-pointers ? 

4. Examine more closely the pollen masses. Notice 

particularly their adhesive inner surface. Observe 
the form and structure of the stigma, and see 
how the pollen is retained when applied to its 
surface. 

5. Endeavor to interpret these peculiar arrangements. 

If practicable, observe the action of visiting 
insects. 1 

ARETHUSA. Arethusa bulbosa, L. 

Study the flower as directed in the case of Cypripedium, 
with reference to 

I. External features, such as form and position of parts, 
color, odor, etc. 

II. Morphological characters. 

Examine each whorl critically. Determine the plan of 
the flower and note modifications. In what important 
particular does the andrcecium differ from that of Cypripe- 
dium? 

Construct a diagram, and compare with that of the 
flower of Cypripedium. 2 

III. Physiological adaptations. 

While plainly dependent on insects for fertilization, the 
flower of Arethusa presents a very different mechanism 
from that of Cypripedium. Examine carefully the rela- 

1 Cf . Miiller, Fertilization of Floioers, pp. 539-542 ; Gray, Am. Jour. 
Sci., XXXIV (1862), pp. 420-429 ; Darwin, I.e., p. 230. 

2 Cf . Goodale, I.e. 



THE ORCHIS FAMILY. 159 

tive position of anther and stigma, and endeavor to make 
out for yourself how this arrangement prevents the appli- 
cation of its own pollen to the stigma of a given flower, 
and at the same time favors cross-fertilization. 1 

RELATIONSHIP. 

This large family of plants includes about three thousand 
species, widely distributed in both hemispheres, and show- 
ing the highest specialization of the flow^er yet attained in 
the vegetable kingdom. Many of the most conspicuous and 
curious kinds are tropical epiphytes, and are frequently 
cultivated in conservatories. As Miiller points out, the 
family is remarkable for the great differences of habit 
exhibited by the different species, the extraordinary modi- 
fications of its flowers, and the great number of seeds 
produced in a single fruit. The differences of habit, some 
being epiphytic, others saprophytic, and so on, indicate 
great capacity of the vegetative organs for variation, and 
the modifications of the flowers are manifestly correlated 
with the visits of insects. Cross-fertilization is the rule, 
but here again " orchids show the greatest possible differ- 
ences, all of which, however, are linked together by inter- 
mediate conditions. We find in this order, cleistogamic 
flowers and open flowers ; flowers regularly or occasionally 
self-f ertilized ; others never self-fertilized, though quite 
fertile to their own pollen if it be applied artificially ; 
flowers absolutely sterile to their own pollen, though fer- 
tile not only to the pollen of their own species but even to 
that of other species of their own genus ; finally, species 
in which pollinia and stigma of the same individual act 
as fatal poisons to one another." 2 

1 Cf. Gray, How Plants Behave. 
2 Miiller, I.e., pp. 527, 528. 



160 STUDY OF COMMON PLANTS. 

The homologies of the flowers of orchids have been 
discussed at length by Darwin and others. The following 
may be given as a brief resume of the most essential facts : 

Comparing the flower of an orchid with a simpler one, 
such as a lily, the several whorls are seen to have under- 
gone varying degrees of modification. The three sepals 
are readily identified, although they are usually petal-like 
in structure, and two, or sometimes all three, may have 
undergone coalescence. Of the three petals, the two 
lateral ones are alike, while the third, called the lip, is 
enlarged and differs widely in form from the other two. 
The essential organs are consolidated into a single body, 
the column. In the genus Cypripedium one stamen has 
become abortive, while the two remaining ones produce 
pollen ; in the other genera of the family only one stamen, 
as a rule, is perfect. The ovary shows its origin in three 
carpels ; but it is one-celled, and the three placentae are 
parietal. 

Theoretically it is held that originally the stamens were 
in two whorls of three each, and that in Cypripedium the 
staminode (abortive stamen) belongs to the outer whorl 
and the two fertile ones to the inner, while in other 
genera, in the great majority of cases, this relation is 
reversed. For a brief but satisfactory statement of this, 
with good diagrams, see Luerssen, Botanik, p. 469. 



THE WILLOW FAMILY. 161 



XXI. THE WILLOW FAMILY. SALICACE^E. 

MATERIAL REQUIRED. 

Branches of the earliest flowering willow, Salix discolor, Muhl., gath- 
ered in the early spring before the leaves appear. Specimens 
with both staminate and pistillate flowers are wanted. (Salix 
cordata, or other species may be substituted. ) Similar branches 
of different kinds of poplar, Populus tremuloides, Michx., and 
other species. 

WILLOWS. 
General Characters. 

Beginning with the willows, observe the various exter- 
nal characters, such as 

1. Form and structure of buds. 

2. Color of the bark. Is it smooth or rough ? 

3. Texture of the twigs. Are they lithe or brittle ? 

Note. — Such characters are frequently of much more impor- 
tance than they appear to be at first sight. The twigs of some 
species of willows are extremely brittle at the base, and being 
easily detached serve as a means of propagation ; while their color 
and surface are sometimes so characteristic as to become an impor- 
tant factor in classification. 

Flowers. * 

I. Examine first the staminate catkins. 

1. Ascertain what constitutes the individual flower. 
(Each flower is subtended by a small hairy scale.) 
Under a lens determine 
a. The shape of the scale. 
6. Whether the margin is cut or entire. 



162 STUDY OF COMMON PLANTS. 

c. Where the numerous silky hairs are attached. 
2. Study the flower itself. 

a. How many stamens are there ? 

b. Is a nectary (organ that secretes nectar) present? 

II. Examine next the pistillate catkins. 

1. In what respects do they differ from the staminate 

ones ? Are the scales alike in both ? 

2. Note the peculiarities of the pistil. 

a. Its form. 

b. Stalked or sessile ? 

c. Number and form of stigmas. 

d. How many carpels compose the ovary ? 

e. Is there a nectary? 

III. Are the flowers visited by insects ? Enumerate the 
attractions adapted to secure insect visits. 1 

Fruits. 

When the fruits are ripe, observe their structure and 
mode of dehiscence, the attachment of the seeds and their 
peculiarities, particularly their means of dissemination. 

Comparison with Other Species. 

Some days later, as soon as they are in proper condition 
for examination, study the catkins of other kinds of willows 
QSalix cordata, Muhl., >S r . lucida, Muhl., or other available 
species), and note all the characters in which they agree 
with the species already studied. 

POPLARS. 

In the same manner make a careful study of one or 
more common species of poplar and compare them with 
the willows. 

1 Cf. Muller, Fertilization of Flowers, p. 524. 



THE WILLOW FAMILY. 163 

I. Note first their external characters and habits, and 
notice in what respects they differ from those of the wil- 
lows. Compare 

1. Bark. 

2. Buds, particularly the surface of the bud-scales. 

3. Leaves. 

4. Branches, as to size, texture, and surface marking. 

II. Carry out, step by step, a thorough comparison of 
the inflorescence and flowers. 

1. How do the scales of the poplar catkin differ from 

those of the willows ? 

2. Do the flowers of the poplar have any structure that 

is wanting to those of the willows ? 

3. Compare the number of stamens in the two genera. 

4. Are their fruits and seeds essentially alike ? 

III. Finally, after several species of each have been 
studied, record all the characters in which willows and 
poplars agree. The characters exhibited by all of them in 
common are those of the willow family (Salicacese). 

SPECIAL STUDIES. 

I. Determination of species of poplar, by means of 

winter buds. 
II. Recognition of different species of willow by size, 
habit, and other external features. 

Note. — The identification of willows and poplars is attended with 
some difficulty, requiring long practice and the exercise of critical judg- 
ment ; but it is desirable that even beginners should observe how readily 
the large-toothed aspen, Populus grandidentata, may be distinguished 
from Populus tremuloides by its bud-scales, how Salix lucida is at 
once recognized by its leaves, and how Salix alba and Salix nigra 
are distinguishable from other species by their size and from each other 
by their habit, even at a distance. Simple exercises of this sort may be 
introduced occasionally with great advantage. 



164 STUDY OF COMMON PLANTS. 



XXII. THE CROWFOOT FAMILY, 
RANUXCULACE^E. 

MATERIAL REQUIRED. 

Specimens of the early crowfoot, Ranunculus fascicularis, Muhl., some 

in flower, others in fruit. 
Similar specimens, as they can be obtained, of Anemone nemorosa, L., 

and Caltha palustris, L. 
Representatives of other genera, such as Hepatica, Clematis, Aquilegia, 

Actsea, Hydrastis, etc. 

EARLY CROWFOOT. Rununculus fascicular is, Muhl. 
Distribution. 

Record what you have observed as to the habitat of this 
species. For the use of the term habitat cf. Gray, Struct- 
ural Botany, p. 366. Do you regard it as indigenous or 
introduced ? 

Note. — This is often a difficult question to settle. We have to de- 
pend partly on recorded observations and partly on what we now see of 
the habits of the plant, the places where it grows, the direction in which 
it spreads, and so on. Trustworthy evidence is attained when competent 
botanists actually observe for a period of years and record the stations 
occupied by the species in question. 

Observations of this kind are of much interest, and if properly con- 
ducted may be made of great scientific value. Constant changes in the 
vegetation of a given locality are taking place, due either to the introduc- 
tion of foreign species or to the disappearance of indigenous plants, as 
the result of changed climatic and other conditions. Some introduced 
plants have so taken possession of territory invaded by them as to become 
formidable rivals of the native species, and even to crowd them out. The 
Canada thistle, prickly lettuce, butter-and-eggs, hound's tongue, and 



THE CROWFOOT FAMILY. 165 

many others are among the undesirable accessions to our native flora, 
some of them extending over wide areas in the course of a few years.. 

In collecting data regarding the distribution of a species, you should 
first of all record where you have seen the plant growing. To this add 
any observations you may have made as to its choice of locality, be- 
havior from year to year, increase in number, liability to extermination, 
etc. To be accepted as trustworthy, notes of this kind must be accom- 
panied by specimens. 

With perfect specimens at hand examine the parts of 
the plant in order. 

Roots. 

Describe their shape. What direction do they take? 
How do those of last year differ from those of the present 
year? Are there any fine, fibrous roots? if so, where do 
they arise ? 

Note. — A comparison of different specimens shows an interesting 
division of labor. 

The smaller fibrous roots absorb from the soil water and crude mate- 
rials that are passed on to the leaves. In the latter, starch and other 
reserve substances are produced, and are then carried down to the spindle- 
shaped roots where they are stored until the next year. At the time of 
flowering the roots of last year have already become exhausted, and look 
old and wrinkled, while the new ones that are to take their place have 
not nearly attained their full size. There are, then, three different sets 
• of roots performing as many different functions. One set is absorbing, 
another is feeding the rapidly growing plant, and the third set is develop- 
ing into a storehouse in which will be laid up during the summer a supply 
of food for future use. 

Leaves. 

Most of the leaves arise from a very short stem, and 
appear as if they grew directly from the roots ; accord- 
ingly they are described as " radical." One or more leaves 
are borne on the flowering stems and are spoken of as 
" cauline," 



166 STUDY OF COMMON PLANTS. 

I. Describe first the radical leaves. Compare specimens 
and see whether the same description will answer for all 
of them. 

II. Examine the cauline leaves of a number of different 
individuals and note the various forms. 

III. Are there any means of protection? 

Note. — Do not answer the qnestion hastily. Hairs on delicate plants 
sometimes protect their tissues against cold, sometimes against small, 
soft-bodied animals that might devour them or climb up to the flowers 
and steal the nectar, and again, the presence of acrid juice may render 
them distasteful to grazing animals. See, if you can, whether this plant 
is protected in any or all of these ways. 

Flower. 

Study first the plan of the flower. Are all the parts 
present? Is it a " regular " flower ? Has any consolida- 
tion of parts taken place, or are they all free and distinct? 
Describe by a single word the insertion of the floral en- 
velopes. 

Next, examine and describe in detail the successive 
whorls. 

I. Calyx. How many sepals are there? Is this num- 
ber constant? Describe their shape, color, and surface. 
How does their position on the flower bud correspond with * 
that taken when the flowers are fully expanded ? From 
its earlier condition do you infer anything as to the func- 
tion of the calyx ? 

II. Corolla. Does the number of petals correspond 
with the number of sepals ? Remove two or three and 
examine them under a lens. Draw one in outline, taking 
care to represent the little scale near the point of insertion. 

Examine the scale carefully. Lift up the free edge 
with the point of a needle. Frequently a small drop of 



THE CROWFOOT FAMILY. 167 

nectar can be found at its base. The whole arrangement 
constitutes a simple and efficient device for protecting* the 
nectar, and, at the same time, leaving it accessible to visit- 
ing insects. 

III. Stamens. How many? Are they all alike? In 
what order do they ripen? Study under a lens the mode 
of dehiscence of the anthers. It will usually be found 
that such facts, apparently trivial, are really important. 
In the present case, after the oldest stamens begin to 
shed their pollen, some little time elapses before the 
youngest ones are mature, thus ensuring a supply of 
pollen for visiting insects several days in succession, and 
insects climbing over the flowers can hardly fail to carry 
pollen from one to another. 

IV. Pistils. Study these in flowers of different ages. 
It will be an advantage to make longitudinal sections of 
the flower. Notice 

1. The elongated axis, receptacle, on which the pistils 

are inserted. 

2. The shape of the pistils. Draw an enlarged outline 

of one. 

3. In those that have been properly sectioned the single 

ovule. Examine the latter in still older specimens 
and satisfy yourself regarding its form, point of 
attachment, and direction taken in the ovary. 
Compare mature fruits and seeds if they are to 
be had. 
Read Miiller, Fertilization of Floivers, p. 74 et seq. 

RELATIONSHIP. 

We have next to study some of the immediate relatives 
of the early crowfoot. This may be done at the same 



168 STUDY OF COMMON PLANTS. 

time, if specimens are procurable, otherwise comparisons 
should be deferred until a full supply of material is at 
hand. 

I. We take first the wood anemone, Anemone nemo- 
rosa, L. 

The anemone rises from a creeping rhizome that gives 
off fine, fibrous roots. The simple stem bears a three- 
leaved involucre and a single conspicuous flower. Each 
leaf of the involucre is petiolate, without stipules, and 
divided into three leaflets that are variously cut and 
toothed, the lateral ones often divided nearly or quite to 
the base. Similar radical leaves arise from the rhizome. 
The flower has a calyx consisting of five or six (frequently 
more) white sepals, that are often tinged with pink, many 
distinct stamens, and a less number of carpels (15-20). 

See if your specimens agree throughout with the de- 
scription just given. Name all the points in which the 
anemone and early crowfoot agree and those in which 
they differ. Incidentally observe the arrangements for 
securing fertilization. 1 

II. Continuing our comparative study, we next take 
the marsh marigold, Caltha palustris, L., and in the same 
way compare it throughout with the anemone and early 
crowfoot, noting as before all points of difference and 
resemblance. Widely as the vegetative parts differ, it 
is obvious that the flowers of all three species are almost 
identical in their essential structural features. 

The marsh marigold presents several attractive features, 
and cross-fertilization is effected through the agency of 
insects, but self-fertilization may also take place. Cf. 
Muller, pp. 79, 80. 

1 Cf. Muller, Fertilization of Flowers, pp. 72, 73. 



THE CROWFOOT FAMILY. 169 

III. If practicable, the comparison should be extended 
to a number of other species belonging to different genera, 
as, for example, Hepatica triloba, Ohaix, Anernonella thalic- 
troides, Spach, Clematis Virginiana, L., Aquilegia Cana- 
densis, L., Actcea alba, Bigel, Hydrastis Canadensis, L., 
and any other plants of this family, wild or cultivated, 
that may be available. 

CHARACTERS OF THE RANUNCULACEiE. 

After such a comparative study, embracing as many 
species as possible, we may sum up the characters that 
distinguish members of this family as follows : 

1. Chiefly herbaceous plants. 

2. Juice watery, in many species acrid and poisonous. 

3. Leaves generally compound or variously cut and 

divided, without true stipules, but frequently 
dilated at the base. 

4. All parts of the flower free and distinct. Corolla 

often wanting. Floral envelopes and numerous 
stamens hypogynous. 

5. Carpels numerous or few, forming achenia, berries, 

or follicles in fruit. 1 

This family of plants is of interest • in many ways. 
Owing to their active properties many of the species 
such as gold-thread, black hellebore, aconite, larkspur, and 
Hydrastis are employed medicinally. In fact these active 
properties constitute an important feature of their relation- 
ship. The order furnishes a number of ornamental plants 
common in cultivation, such as Clematis, columbine, monks- 
hood, and others. The color of the flowers, yellow and 
white in many of the simpler species, passing into red and 
1 Cf. Gray, Manual, p. 34. 



170 STUDY OF COMMON PLANTS. 

blue in the more highly developed ones, taken in connec- 
tion with the striking modifications of form by which the 
latter have become more and more perfectly adapted to 
the visits of insects, gives some support to the theory 
called the Law of Progressive Coloration. 1 

SPECIAL STUDIES. 

I. Colors of flowers belonging to the Ranunculacese. 

II. Various degrees of adaptation to fertilization by the 
agency of insects in this family. Is self-fertiliza- 
tion possible in the majority of cases ? Is it impos- 
sible in any species ? 

III. Fruits of the Ranunculaceae. 

IV. Dissemination of seeds. Special arrangements in 

Clematis and other genera. 

1 Cf . Grant Allen, Colors of Flowers, pp. 17-60 ; Miiller, Fertiliza- 
tion of Flowers, pp. 88, 89. 



THE MUSTARD FAMILY. 171 



XXIII. THE MUSTARD FAMILY. CRUCIFER^E. 

MATERIAL REQUIRED. 

Entire plants of Shepherd's-purse, Capsella Bursa-pastoris, Moench, 
with both flowers and frnit. 

Specimens of any of the following species that can be obtained : 
Spring Cress, Cardamine rhomboidea, DC. ; Pepper-root, Dentaria 
diphylla, L. ; Water Cress, Nasturtium officinale, R. Br. ; Sweet 
Alyssum, Alyssum maritimum, Lam.; Rocket, Hesperis matronalis, 
L. ; Peppergrass, Lepidium Virginicum, L. ; Hedge Mustard, Sisym- 
brium officinale, Scop. ; Wild Mustard, Brassica Sinapistrum, Boiss. 

SHEPHERD'S-PURSE. Capsella Bursa-pastoris, Moench. 
Distribution, 

Record your own observations as to the occurrence and 
habits of this plant. Does it manifest a preference for 
any particular soil or locality ? 

General Characters. 

Write an accurate description of the root, stem, leaves, 
and inflorescence. 

Flower and Fruit. 

I. Study the plan of the flower, noting the number and 
arrangement of sepals, petals, and essential organs. Show 
the application of the word " cruciform " as used to 
describe the corolla. Are the stamens all alike ? 

II. Examine the structure of the ovary. Compare it as 
it appears in the flower, with partially and fully developed 



172 STUDY OF COMMON PLANTS. 

fruits. How many carpels are there ? Attachment, 
direction, and form of ovules? Mode of dehiscence? 
How is the fruit to be classified? 

III. Construct a diagram of the flower. 

IV. Compare the views of different writers regarding 
the morphology of the flower of Cruciferse. 1 

RELATIONSHIP. 

I. Compare with shepherd's-purse such of the species 
named above as can be procured, and determine what 
characters they exhibit in common. Do they all have a 
pungent juice ? Are they all herbaceous ? Are the flowers 
on the same plan ? How far do the fruits and seeds agree 
in structure ? 

II. Summarize the results of your observations in a 
brief general description of cruciferous plants. 

Note. — To complete this comparative study at all satisfactorily will re- 
quire much time and patience. In studying the seeds it will be best to 
obtain those of different genera from the seed store, sow a part of them 
in moist sawdust, and dissect carefully from day to day. If the time is 
short, it may be best to limit the comparison to a very few species, but 
if even two or three genera are thoroughly studied, and the descriptions 
accompanied by floral diagrams and sketches of the structure of fruits 
and seeds, the student cannot fail to be impressed, as in no other way, 
with the persistent and marked features of this remarkable group of 
plants. 

The flowers of the Cruciferae, notwithstanding their 
great uniformity of structure, exhibit striking physiologi- 
cal differences. The number and position of the nectaries 
is extremely variable. Some have a strong odor, and in at 
least one species this is associated with evening expansion 

1 Cf. Gray, Structural Botany, pp. 206, 207 ; Arthur, Barnes, and 
Coulter, Plant Dissection, p. 238 (references in footnote). 



THE MUSTARD FAMILY. 173 

of the flower. One has become distinctly anemophilous, 
although giving plain evidence of having descended from 
entomophilous ancestors. 1 

1 Cf. M tiller, Fertilization of Flowers, pp. 100-114 ; Hooker, Nature, 
Yol. X, p. 134 ; Eichler, Bluthendiagramme, pp. 200, 206. 



174 STUDY OF COMMON PLANTS. 



XXIV. THE ROSE FAMILY. ROSACEA. 

MATERIAL REQUIRED. 

Flowering shoots of the cultivated cherry, and, as soon as they are 
in full bloom, those of the peach, plum, apple, and pear. 

Representatives of the following genera, as far as they can be ob- 
tained in flower or fruit ; Fragaria, Physocarpus, Potentilla, Geum, 
Rubus, Rosa, Crataegus. 

THE CHERRY. Prunus Cerasus, L. 
Distribution. 

The cultivated cherry is familiarly known in the north 
temperate zone of both hemispheres. For the evidence 
regarding the region to which it is indigenous, see De 
Candolle, Origin of Cultivated Plants, pp. 206-210. 

Flower and Fruit. 

I. Study the parts of the flower in succession, noting 
their form and insertion, the union of parts, and other 
modifications if such exist. 

II. Make a longitudinal section and draw it accurately. 
Is any nectar to be found ? If so, are there any arrange- 
ments for its protection ? 

III. Make longitudinal sections of a number of ovaries 
and transverse ones of others. Determine the number of 
ovules, their form and place of attachment. Draw. Com- 
pare the number of ovules in flowers just opened and in 
those that are fading or have lost their corolla. 



THE ROSE FAMILY. 175 

IV. Construct a diagram of the flower. 

V. Does the structure of the flower present any adap- 
tations to the visits of insects ? 

VI. How is the dissemination of seeds provided for ? 

RELATIONSHIP. 

I. With the cherry compare first the cultivated plum, 
in flower about the same time. 

1. Note every point of difference between the two 

species, giving special attention to the structure 
of the flower. 

2. Observe the points in which they agree. 

II. Compare the flowers of the peach with those of the 
cherry and plum, noting the features in which all agree 
and those in which they differ. 

III. Examine next the flowers of the pear or apple. 
Make a longitudinal section, draw it and compare with 
that of the cherry flower. Make successive cross-sections 
of the ovary till one is found that shows the ovules clearly. 
Draw and compare with similar sections of the ovary of 
the cherry. 

IV. Make a similar study of the flowers of the straw- 
berry. Indicate all the points in which they differ from 
those of the cherry and apple. Compare longitudinal 
sections of all three. 

V. Having made a further comparative study of as 
many of the plants of this family as are available, sum- 
marize the characters that you have found to be general, 
taking leaves, fruit, etc., into account as well as the 
flowers. % 



176 STUDY OF COMMON PLANTS. 

If enough species have been examined the characters 
thus derived will be those of the Rosaceae or Rose Family, 
a large and important natural order, furnishing a large 
proportion of the fruits of the north temperate zone, 
numerous ornamental species, among them the rose, 
spiraea, hawthorn, and mountain-ash, and some medicinal 
plants, including the wild cherry and others. 

The flowers of the various genera exhibit interesting 
peculiarities of color and structure corresponding to the 
different degrees of adaptation to insect visitors. 1 

SPECIAL STUDIES. 

I. Development of a cherry. This involves a study 

of the ovary and its changes during the entire 
period of the formation of the fruit. Sections of 
different specimens should be made at frequent 
intervals, and a series of drawings kept with their 
accompanying dates. 

II. A similar study of the development of the apple. 

III. How far the production of our domestic fruits is 

dependent on the agency of insects. 

IV. Evidence regarding the "law of progressive colora- 

tion " drawn from the flowers of this family. 2 

V. Collection and classification of the indigenous rosa- 
ceous plants of the region in which the study is 
carried on. 

VI. Origin and varieties of the cultivated strawbercy. 

VII. Extra-floral nectaries and their use. 

1 Cf. Miiller, Fertilization of Floicers, pp. 242, 243. 

2 Allenf^Colors of Floioers, p. 25 et spq. 



THE PEA FAMILY. 177 



XXV. THE PEA FAMILY. LEGUMINOS^. 

MATERIAL REQUIRED. 

Entire specimens of the wild lupine, Lupinus perennis, L., in flower. 
Flowers, leaves, and fruits of some or all of the following species : 
Robinia Pseudacacia, L. ; Vicia Caroliniana, Walt. ; Trifolium pra- 
tense, L. ; Melilotus alba, Lam. ; Lathyrus palustris, L. ; Lathyrus 
odoratus, L. 

WILD LUPINE. Lupinus perennis, L. 

Distribution and General Characters. 

Note locality and habits. Is this species indigenous or 
introduced ? Describe in detail stem, leaf, and inflo- 
rescence. 

Flower. 

I. How many divisions has the calyx ? Is its surface 
smooth or hairy ? 

II. With a number of good specimens at hand, observe 
in their natural position the parts of the corolla, their 
form, color, and relations to each other. They have 
received special names that must be made familiar. The 
conspicuous upper petal is called the standard, vexillum, 
the two lateral ones are the wings, alse, while the two lower 
ones are united to form the keel, carina. 

III. Examine critically each of these parts. 

1. Are there any grooves or ridges on the standard? If 
so notice their form and direction. See if there 



178 STUDY OF COMMON PLANTS. 

are any lines or dots likely to serve as path 
pointers. Compare the color of the standard of a 
number of flowers. 
2. Observe the form and structure of the wings. Re- 
move one and sketch its outline. In an unin- 
jured flower, notice particularly how the wings 
are fitted to the keel and standard. 

IV. With a pencil, or other instrument, push the wings 
downward with some force, imitating the action of a heavy 
insect. Repeat the operation on different specimens until 
its result is clearly seen. 

V. See if you can understand how it is that the wings 
and keel return to their position when the pressure is 
removed, and whether there is any advantage in this. 

VI. Examine next the structure and mechanism of the 
essential organs. 

1. Remove the floral envelopes from the side of the 

flower, leaving the other parts undisturbed. The 
stamens and pistil can now be studied to advan- 
tage in their natural position. 

2. Count the stamens. Are they monadelphous or dia- 

delphous ? Are they all alike ? Compare those 
of flowers about to open with younger and older 
ones. 

3. Look at the end of the keel of uninjured flowers. 

Where is the pollen stored after the dehiscence 
of the anthers ? Examine and describe the mech- 
anism by which it is pushed out when the keel is 
opened. 

4. Observe next the shape of the pistil, the direction 

taken by the style, and the surface of the latter as 
seen under a lens. 



THE PEA FAMILY. 179 

i 

5. Finally, with a number of perfect specimens of dif- 
ferent ages, study the whole mechanism. -Write 
a complete account of the structure of the flower 
and the mechanical arrangements favoring cross- 
fertilization, making outline sketches whenever 
it is necessary to render the description more 
intelligible. 1 

RELATIONSHIP. 

As the flowers of different plants belonging to the pea 
family are to be had, compare their structure and mech- 
anism with those of the lupine. Any of the species 
named above, the common locust for example, in flower a 
little later than the lupine, will present interesting points 
for comparison. 

1. Do corresponding whorls of the flowers of different 
species agree as to position, form, and number of parts ? 

2. Is the mechanism by which fertilization is accom- 
plished essentially the same as in the lupine? 

3. In specimens that are past flowering, study the fruit 
in early and later stages of development. 

4. Observe the position and form of the ovules, and, 
in older specimens, the mode of dehiscence of the fruit. 

5. Aside from characters drawn from flowers and fruit, 
determine whether leaves of the different species present 
any common features. 

6. Summarize the results of your comparative study in 
a brief statement of the characters common to those mem- 
bers of the Leguminosse that you have become acquainted 
with. 

1 Cf. Muller's account of Lupinus luteus, the structure of which is 
much like that of Lupinus per 'ennis, Fertilization of Flowers, p. 187. 



180 STUDY OF COMMON PLANTS. 

i 

The Leguminosse constitute a large and remarkable 
family of plants, including between six and seven thou- 
sand species, distributed throughout the world, but most 
abundant in tropical regions. Many of the species are of 
economical interest. The various kinds of clover furnish 
important forage crops, and peas, beans, and lentils form an 
almost indispensable constituent of the food plants of the 
world. Dye woods and drugs are yielded by a consider- 
able number. Some are exceedingly poisonous, among 
them the famous ordeal bean of Calabar. Botanically they 
are of special interest for the peculiarities of the mechanism 
by which their flowers are adapted to cross-fertilization. 
A large proportion, too, of plants whose leaves exhibit 
" sleep movements " belong to this family. 

SPECIAL STUDIES. 

I. Arrangements for cross-fertilization in the Legu- 
minosse. 
II. Extent to which the production of seeds of red 
clover is dependent on the agency of insects. 

III. Capacity of the common pea for self-fertilization. 

IV. Occurrence of modified leaves, such as tendrils, 

phyllodes, etc., among the Leguminosae. 
V. Morphology of protective structures of various legu- 
minous plants, e.g. spines of locust and honey 
locust, prickles of Schrankia, and hairs of Des- 
modium. 
VI. Sleep movements of clover, lupine, and other plants 
of this family. 
VII. Affinities of the Leguminosae. 
VIII. Causes of the wide distribution of this family. 
IX. Varieties of cultivated peas and beans. 



THE GERANIUM FAMILY. 181 



XXVI. GERANIUM FAMILY. GERANIACE^E. 

MATERIAL REQUIRED. 

Specimens of horseshoe geranium, Pelargonium zonale, L., in flower. 
Wild cranesbill, Geranium maculatum, L. ; Nasturtium, Tropceolum 

majus, L. ; Touch-me-not, Impatiens fulva, Nutt., or cultivated 

balsams that have not become double. 

HORSESHOE GERANIUM. Pelargonium zonale, L. 

Distribution. 

The " horseshoe geranium " is universally cultivated. 
In common with various other cultivated species of the 
same genus, it is indigenous to southern Africa. Very 
many varieties have been produced. 

General Characters. 

With good specimens, observe and describe the various 
external features, such as 

I. Mode of branching. 
II. Leaf arrangement. 

III. Presence or absence of stipules. 

IV. Form of leaves. 

Inflorescence. 

Taking care to select plants the flowers of which have 
not become double, compare inflorescences of different 
ages, and ascertain the order of development of the flowers. 



182 STUDY OF COMMON PLANTS. 

Note. — Like many other facts usually treated as morphological, the 
character of the inflorescence is of much physiological importance. 
The successive opening of the flowers in regular order, instead of simul- 
taneously, insures a much longer period of time during which fertilization 
may take place, and their position and aspect when ready for pollination 
are most frequently such as to render them conspicuous and easily acces- 
sible to insect visitors. The latter, while gathering honey, are often 
observed to proceed in a methodical manner corresponding to the order 
of development of the flowers. 

Flower. 

I. Study the structure and plan of the flower. Is it 
perfectly regular ? 

Note. — Give special attention to this point. The beginnings of irregu- 
larity are of great interest, since they give us a clue to the way in which 
some of the most efficient mechanical contrivances in the vegetable king- 
dom have originated. 

II. Study next the ovary. 

1. Cut transverse and longitudinal sections of ovaries of 

various ages. 

2. Make out the form and place of attachment of the 

ovules. 

3. In the partially developed fruit examine the imma- 

ture seeds, and note the form and position of the 
embryo, easily recognized by its green color. 

4. Construct a diagram of the flower. 

Physiological adaptations. 

I. Examine with a good lens the surface of stem, leaves, 
flower-stalk, and calyx. Are there any distinctively pro- 
tective arrangements? 

II. In what ways is the inflorescence adapted to cross- 
fertilization ? Notice the position of the open flowers as 
contrasted with that of the flower buds. Effect of " mass- 
ing." 



THE GERANIUM FAMILY, 183 

III. Study the flower itself with reference to the same 
question. Compare the color of different specimens, and 
varieties. Is there anything to indicate to a visiting insect 
the way to the nectar ? Find the nectar-tube and explore 
with a bristle. 

Xote. — Some specimens have a nectar-tube united with the pedicel 
and easily recognizable on the outside, either by its color or by its form- 
ing a longitudinal ridge. In others it is not readily found. Even flowers 
of the same inflorescence differ in this respect. 

IV. Compare the stigmas of older flowers with those in 
which the anthers are just shedding their pollen. Are the 
flowers proterandrous or proterogynous ? 1 

V. Study the structure of the mature fruit, and ascer- 
tain how the seeds are disseminated. 

Note. — The geranium lends itself readily to experiments in cross- 
fertilization, and the student who has opportunity is advised to cross two 
widely different varieties and compare the growth and vigor of the crossed 
seedlings with that of seedlings derived from self-fertilized flowers. 
Read the chapter on Pollination in Professor L. H. Bailey's Nursery Book. 



RELATIONSHIP. 

I. Compare the plant just studied with the wild cranes- 
bill, noting points of agreement and difference. Give 
special attention to the flowers of the two genera, examin- 
ing them whorl by whorl, until you are satisfied regarding 
their differences. Record these in detail. Refer in this 
connection to Mailer's 2 or Lubbock's 3 account of various 
species of Geranium. 

1 Cf. Darwin, Cross- and Self-fertilization in the Vegetable Kingdom, 
p. 142. 

2 Fertilization of Flowers, pp. 149-158. 

3 British Wild Floivers in Relation to Insects, pp. 43, 44, 72-74. 



184 STUDY OF COMMON PLANTS. 

II. Compare next the cultivated nasturtium, Tropceolum 
majus, L., with the horseshoe geranium. 

1. Note the very different habits of the plant, the pecu- 

liarities of its foliage leaves, and means of pro- 
tection. 

2. Observe the structure and plan of the flower. Note 

particularly the color of both calyx and corolla, 
the guiding lines, nectar-tube, mode of guarding 
the entrance to the latter, dichogamy, structure 
of ovary, and number of carpels. 1 

III. In addition to the foregoing, study if possible one 
or more indigenous species of Impatiens, or forms of the 
cultivated " balsam " that have not become double. They 
are of special interest as regards both the peculiar modi- 
fications of the flower and the mechanism of seed dissemi- 
nation. 

1. Comparing the plan of the flower with that of the 

species previously studied, try to ascertain whether 
there has been consolidation or suppression of 
parts, or both. 

2. Does the structure imply adaptation to cross-ferti- 

lization? Does dichogamy exist? 

3. If opportunity permits, observe what visitors Impati- 

ens has and their mode of operation. 

4. Examine ripe fruits and investigate the mechanism 

of seed dissemination. Is it the same in principle 
as in Pelargonium and Geranium? 2 

Note. — The relationship of Pelargonium with the closely 
allied genus Geranium is obvious, but it differs in important 

1 Cf. Lubbock, I.e., pp. 75, 76. 

2 Cf. Duchartre, Elements de Botanique, p. 791. 



THE GERANIUM FAMILY. 185 

particulars from Tropseolum and Impatiens, both of which, in 
recognition of their wide departure from more primitive, forms, 
are now placed in separate families. The study of such a series 
of forms is in the highest degree instructive, presenting as it 
does very important evidence regarding the descent of these 
peculiarly modified genera. 



186 STUDY OF COMMON PLANTS. 



XXVII. THE SPURGE FAMILY. 
EUPHORBIACEJE. 

MATERIAL REQUIRED. 

Spurge, Euphorbia Cypaiissias, L., and other species of Euphorbia. 
Representatives of other genera of the same family as far as these 
are procurable. 

SPURGE. Euphorbia Cyparissias, L. 
Distribution. 

In what situation is this plant usually found growing ? 
Have you observed anything as to its persistence from 
year to year, where it has once become established ? Do 
its habits indicate that it is an indigenous species ? 

General Characters. 

Study the general features of the plant and write a brief 
description. In addition to the ordinary botanical char- 
acters note particularly 

1. The way in which new shoots arise. 

2. The abundant latex in every part. 1 

3. The great variety of foliar organs — scale leaves, 
foliage leaves, and floral leaves — and their form, position, 
and color. 

Inflorescence and Flowers. 

The morphology of the flower in this family has been 
the subject of much discussion and an extended literature. 

1 Care should be exercised in handling spurges as the juice is poisonous. 



THE SPURGE FAMILY. 187 

Without attempting at the outset a critical theoretical 
study, we shall simply undertake to observe the -floral 
organs as they are, and give to them their commonly 
accepted names. Book descriptions and figures are best 
left alone until the plant has been studied at first hand. 

I. Observe first the general arrangement of the inflores- 
cences. They are borne on long slender stalks that arise 
close together near the apex of the stem, and present 
collectively the general appearance of an umbel. Is it 
strictly an umbel ? 

II. The slender stalks each bear near their extremity a 
pair of heart-shaped, yellowish, floral leaves. Notice care- 
fully what there is above the floral leaves. Compare a 
number of specimens of different ages. Do you find still 
other floral leaves? If so, do they resemble the first pair 
in shape and color ? Floral leaves of the second and third 
order are of common occurrence. Do you find any of a 
higher order? 

III. Having found all the floral leaves, we come to the 
inflorescence proper. It greatly resembles a small flower, 
and was described as such by some of the older botanists. 
The cup-shaped structure that looks like a calyx is really 
an involucre. Notice the four " crescent-shaped glands" 
and their position on the involucre. 

IV. Remove enough of the involucre to expose the 
small flowers within. Do this with several specimens of 
different ages. With a lens, examine the minute staminate 
flowers. Note their position and number, the form of the 
anther, and the point where the short filament is con- 
nected with the long pedicel. (Each staminate flower 
consists of a single stamen, mounted on a distinct 
pedicel.) 



188 STUDY OF COMMON PLANTS. 

V. The single pistillate flower is far more conspicuous 
than the staminate ones. As the ovary develops it pro- 
trudes beyond the involucre, so that the entire flower is 
easily studied. Observe 

1. The form of the ovary. 

2. The number of styles and stigmas. 

3. The number of cells in the ovary, as seen in cross- 

section, and the number and position of the 
ovules. 

VI. With a number of entire plants review all that we 
have learned about the species. See that all the facts are 
clearly in mind, and that you are able to designate each 
part by its proper name. Do you consider the plant well 
adapted to survive in the struggle for existence ? If so, 
show how. 

RELATIONSHIP. 

With the species already studied compare other mem- 
bers of the genus such as Euphorbia corollata, L., E. 
marginata, Pursh, E. maculata, L., and one or more repre- 
sentatives of other genera, as, for example, Acalypha 
Virginica, L., and the cultivated castor-oil plant, Ricinus 
communis, L. (The seeds of the latter are of large size, 
and are more easily studied than those of the spurge.) 

Having compared as many species as practicable, see 
how far the characters you have found to be common 
to all agree with the family characters as given in the 
manuals. 

Euphorbia Cyparissias is a familiar representative of a 
large and peculiar family of plants. It is found in patches 
by roadsides and old dwellings where it has escaped from 
cultivation. Its copious milky juice, narrow leaves, and 
tufted habit have given it the common name of " milk- 



THE SPURGE FAMILY. 189 

moss," in addition to that of "spurge," which it shares 
with numerous other species of the same genus. The 
family to which it belongs is chiefly tropical, and is one 
of the few that are specially distinguished by their poison- 
ous properties. Cases of poisoning as a result of handling 
species cultivated for ornament are not infrequent. It 
includes a number of species with powerful medicinal 
properties, and others that furnish valuable food products, 
while the fleshy Euphorbias, the Poinsettia, and others, 
are well-known ornamental plants. 



190 STUDY OF COMMON PLANTS. 



XXVIII. THE MAPLE FAMILY. ACERACE^. 

MATERIAL REQUIRED. 

Flowers of the different species of maples as they open in the spring. 
Fruits of the sugar maple gathered after they have fallen from the 

trees in the autumn. Fruits of the red and silver maples gathered 

in the summer. 
Leaves of all the species. Either fresh or pressed specimens of the 

latter will serve. 

Flowers. 

The flowers of the red maple open early in the spring 
and may be taken first. Specimens should be gathered 
from a number of trees so as to have the different forms of 
flowers for comparison. 

I. Observe the position of the flower bud and the color 
and position of the bud-scales. 

IT. Compare the flowers of different trees. Select 
first, for critical study, those that have well-developed 
stamens. 

1. How many divisions of the calyx are there? Of the 

corolla ? 

2. Is this number the same in all the specimens ? Does 

it correspond with the number of stamens ? 

3. How are the stamens inserted? 

4. Is there a pistil ? 

5. Are there any organs for the secretion of nectar? 



THE MAPLE FAMLLY. 191 

III. Next take specimens that have well-developed 
pistils. 

1. Are stamens present? If so, how do they compare 

with those of the flowers previously studied ? 

2. Are the floral envelopes alike in all the flowers ? 

3. Notice the form and structure of the pistil. How 

many carpels are there? How many ovules in 
each cell ? 

IV. Compare with these the flowers of the silver maple, 
noting carefully all the points" of likeness and difference. 

1. Are petals present? 

2. Do all the flowers have both stamens and pistils? 

3. Is the ovary smooth or hairy ? 

4. Does it agree in structure with that of the red 

maple ? 

5. Do different specimens exhibit any variation as to 

the number of carpels ? 

V. Compare flowers of the sugar maple, which open 
some days later, with those of the red and silver maples. 

1. Are there any differences as regards 

a. Form and position of the flower clusters ? 

b. Color of the calyx? 

c. Structure of the essential organs ? 

2. Are all the flowers of the same tree alike ? How is 

it with those of the red and silver maples in this 
respect ? 
The maples are described as being " polygamo-dice- 
cious." What is meant by this ? Do you find that 
the facts correspond with the statement? 
Fruits. 

Study next fruits, taking first those of the sugar maple 
gathered the preceding fall. 



192 STUDY OF COMMON PLANTS. 

With the fruits of the sugar maple, compare those of 
the red and silver maples, rioting all the external and 
structural differences by which they may be distinguished. 

Leaves. 

Compare the leaves of all three kinds until you are able 
to distinguish the species at sight by means of the leaves 
alone. 

Finally review the observations made thus far, see if 
anything is to be added, and write a complete account 
of the characters common to all three species and also of 
those peculiar to each. 

SPECIAL STUDIES. 

I. Critical comparison of the Box-elder, Negundo 

aceroides, Mcench., with the maples. Does it have 

the essential characters of a maple ? 

II. Polygamous plants. Cf . Darwin, Different Forms of 

Flowers on Plants of the Same Species, Chap. VII. 



THE MALLOW FAMILY. 193 



XXIX. THE MALLOW FAMILY. MALVACEAE. 

MATERIAL REQUIRED. 

Common mallow, Malva rotundifolia, L., in flower and fruit. 

Other representatives of the family, such as Hollyhock, Altlicea rosea, 
Cav. ; Shrubby althaea, Hibiscus Syriacus, L. ; Musk mallow, 
Malva moschata, L. ; Velvet-leaf, Abutilon Avicennce, Gsertn. 

COMMON MALLOW. Malva rotundifolia, L. 

Distribution. 

In what situation is this plant generally found ? Have 
you any evidence as to whether it is an indigenous or 
introduced species ? 

General Characters. 

I. Study first the habits of the plant and note its char- 
acteristic features. 

1. The strong taproot. 

2. Position and direction of the numerous branches. 

3. Presence or absence of stipules. 

4. Form and venation of leaves. 

5. Position and character of inflorescence. 

6. The remarkably strong bast fibers. 

7. Mucilaginous contents, particularly of the fruits. 

II. Enumerate any advantages that this plant possesses 
in competition with others. Is it easily eradicated? Why? 
Is it attractive to grazing animals ? 



194 STUDY OF COMMON PLANTS. 

Flower. 

I. Examine the flower in various stages of development. 
Note 

1. The plan of the flower and how modified. 

2. The three-leaved involucel, " like an outer calyx." 

3. Insertion of the corolla and the relation of the latter 

to the stamen-tube (best seen on longitudinal sec- 
tion). 

4. The monadelphous stamens. 

5. Form and mode of dehiscence of anthers. 

6. Number of stigmas. Does this correspond with the 

number of divisions of the ovary? 

II. Ascertain whether there are any adaptations favor- 
ing cross-fertilization, or any that render self-fertilization 
impossible. 

1. Are there any guiding lines? 

2. Is nectar produced? If so, is it protected in any 

way? 

3. Compare flowers of different ages and ascertain 

whether dichogamy exists. 1 

Fruit and Seed. 

I. Examine the fruit, making both transverse and longi- 
tudinal sections of specimens of different ages. Ascertain 

1. The number of carpels. 

2. Form and place of attachment of the ovules. 

3. Structure and position of the embryo. (This is 

easily made out with a lens by means of repeated 
sections, trying different specimens until the most 
favorable ones are found.) 

1 Lubbock, British Wild Flowers in Relation to Insects, p. 41 ; Miiller, 
Fertilization of Flowers, pp. 142, 143. 



THE MALLOW FAMILY. 195 

II. Ascertain approximately the number of seeds pro- 
duced by a single strong plant. 

RELATIONSHIP. 

Compare with the common mallow at least one, and if 
possible several, of the plants named above, noting the 
various points of difference and likeness. Write a brief 
summary of the characters common to them all. 

The Malvaceae exhibit a number of interesting peculiari- 
ties, some of which indicate relationship with several other 
families, among them the Tiliacece. They are widely dis- 
tributed in both hemispheres, but with a preference for 
the warmer parts of the globe. The cotton plant is the 
most important member of the family, from an economical 
standpoint. A few species are of medicinal value, and a 
considerable number, as Althaea, Hibiscus, Abutilon, and 
others, are well-known ornamental plants. 



196 STUDY OF COMMON PLANTS. 



XXX. THE VIOLET FAMILY. VIOLACE.E. 

MATERIAL REQUIRED. 

Specimens of the cultivated pansy in flower. Indigenous species of 
violets. 

Flower. 

Our study in the present case will be restricted to the 
flower, taking first that of the pansy. 

I. Compare several good specimens as to size and color, 
and observe how far they agree. 

II. Study the, external features of the flower in order. 
Note the number of parts in each whorl, and their peculiari- 
ties of form, structure, and position. 

1. Form of the sepals. Aside from their size and 

position are they readily distinguished from foliage 
leaves ? 

2. Peculiarities of the corolla. To which of the petals 

does the spur belong ? Cut into it and see whether 
it contains anything likely to be of use to the 
flower. What do you conclude as to its function? 

3. Study the disposition of colors. Compare as many 

specimens as practicable. Where do the " guiding 
lines " converge ? 

4. Examine the center of the flower with a lens. 

Notice the thick brush of hairs on either side. 
The position of the essential organs, partially 
visible farther in. 



THE VIOLET FAMILY. 197 

III. Remove carefully the floral envelopes on orie side 
so as to expose the essential organs without disturbing 
them. Notice the relative position of stamens and pistil, 
and their structural peculiarities. The large, rounded 
stigma with an orifice in front. The "lip" forming the 
lower edge of this orifice. The syngenesious anthers and 
their membranaceous connectives united into a tube just 
back of the stigma. The two nectaries projecting into the 
spur. The narrow canal lined with hairs leading from the 
entrance of the corolla back to the spur. 

Jar the stamens and see where the pollen falls out and 
where it lodges. 

IV. Go over all the structures again, in more than one 
specimen, and see if you can determine the use of each 
part of the mechanism. Imitate the action of a bee by 
inserting a slender piece of quill or wood, pushing along 
the groove down to the nectar cavity. Withdraw it and 
see if it brings away any pollen. Insert it into another 
flower and examine the stigma of the latter with a lens 
before and after the operation to see if any pollen has been 
left on it. 1 

V. Make a true longitudinal section of the flower (a 
razor is best for this purpose), and sketch the parts in out- 
line so as .to show their relative position. Name and 
locate each, using letters and guiding lines. 

VI. Make a transverse section of the ovary and examine 
under a lens. Note 

1. The number of placentae. 

2. Number, direction, and form of ovules. If practi- 

cable, compare ripe capsules. 

1 Cf. Sachs, Physiology of Plants, p. 795. 



198 STUDY OF COMMON PLANTS. 

VII. Construct a diagram of the flower. In what 
respects does the pansy differ from a " typical flower," 
as described by Gray, Lessons, pp. 81, 82? 

VIII. Write a full description of the pansy. 

Note. — It is hardly necessary at this stage of the student's progress 
to remind him that a description of such a flower involves much more 
than an enumeration of the parts of each whorl, with an account of 
their surface, outline, etc. An appreciation of the marvelous beauty and 
exquisite adaptations here displayed, and a scientific temper that seeks 
to know how T all this has come to be as it is, will hardly be satisfied with 
mechanically filling the blanks of some "plant analysis." Write as 
though your account were to stand as the only written description of 
the result of a long series of natural experiments, of which we now see 
the culmination in a perfect piece of mechanism. 

IX. Consult the references already given and those 
named under " Special Studies " below. 

RELATIONSHIP. 

As the flowers of various indigenous species appear in 
spring, e.g. Viola palmata, L., V. pedata, L., V pubescens, 
Ait., etc., compare them with the pansy, and note the char- 
acters common to them all. If the green violet, Solea con- 
color, Ging., is to be had, compare this with the true violets. 

Summarize briefly the points in which all these agree. 

SPECIAL STUDIES. 

I. Observation of various insects that visit the pansy. 
Miiller, Fertilization of Flowers, p. 118, gives an 
interesting account of the habits of different bees. 
II. Advantages of crossed over self-fertilized pansies. 
See Darwin's experiments, Cross- and Self-fertili- 
zation in the Vegetable Kingdom, pp. 123-128, 286, 
296, 304. 



THE VIOLET FAMILY. 199 

III. Variation as seen in the cultivated pansy. 'Obser- 

vations of differences of size, shades, and distri- 
bution of color and other peculiarities, even if 
restricted to the pansies grown in a single town, 
give a vivid impression of the extraordinary capac- 
ity for variation and the equally remarkable per- 
sistence of essential features exhibited by this 
species. 

IV. Dissemination of seeds by different species of violets. 

See Lubbock, Flowers, Fruits, and Leaves, p. 5-i 
et seq. 
V. Cleistogamic flowers. See Darwin, Different Forms 
of Flowers on Plants of the Same Species, Chap. 
VIII. 



200 STUDY OF COMMON PLANTS. 



XXXI. THE EVENING-PRIMROSE FAMILY. 
OMGRACE^]. 

MATERIAL REQUIRED. 

Evening primrose, (Enothera biennis, L., in flower. 

Fire-weed, Epilobium anguslifolium, L., Enchanter's-nightshade, Cir- 

ccea Lutetiana, L., and other representatives of the family, such 

as the cultivated Fuchsia. 

EVENING PRIMROSE. (Enothera biennis, L. 

Distribution. 

Where were the specimens obtained? In what other 
places in this country have you seen it growing? Does 
it grow in any other parts of the world ? 1 

Flower. 

I. Examine the whorls in order and draw a diagram of 
the flower. Cut a true longitudinal section, study care- 
fully the relation of the parts, and draw. 

II. Note particularly the very long calyx-tube, insertion 
of petals and stamens, the versatile anthers, elongated 
style, and four thickened divisions of the stigma. 

III. Taking specimens past flowering, cut transverse 
and longitudinal sections of the ovary, and observe under a 
lens the number of rows of ovules in each cell, and their 
form and direction. 

1 Cf. Lubbock, British Wild Flowers in Belation to Insects, p. 93. 



THE EVENING-PRIMROSE FAMILY. 201 

IV. Using still older specimens, observe and describe 
the structure of the fruit and its mode of dehiscence. 

Physiological Adaptations. 

If possible, visit both in the daytime and evening the 
place where the plant is growing, and study its habits. 
Ascertain when the flower opens, whether its color and 
odor are attractive to any particular class of insects, and 
whether the length of the calyx-tube or any other struc- 
tural features indicate special adaptations. Endeavor to 
ascertain by direct observation how pollination is effected. 
Accounts of this, so far, are very meager, but suggest a 
curious keeping in tow of two or more different sorts of 
visitors, some of them coming by day and others by night. 1 

RELATIONSHIP. 

I. Obtain specimens of the great willow-herb, or fire- 
weed, Epilobium angustifolium, L., often very abundant on 
newly cleared land that has been burnt over, and compare 
the plant throughout with what you have seen of the 
evening primrose. Note 

1. Habits and external characters. 

2. Structure of the flower, especially its plan and the 

relation of the various whorls to each other. 

3. Adaptations to insect visitors. Observe particularly 

the position of the stjde in flowers of different 
ages, and the time when the stigmas open. Is this 
before or after the anthers have shed their pollen ? 

Note. — This species furnishes an excellent example of proterandrous 
dichogamy. 2 

1 Cf. Lubbock, I.e. ; Miiller, Fertilization of Flowers, p. 264. 

2 Cf. Gray, Structural Botany, p. 222. 



202 STUDY OF COMMON PLANTS. 

II. Compare the enchanter's-nightshade (Circcea Luteti- 
ana, L.), also in flower in midsummer, with the evening 
primrose. 

1. Construct a diagram of the flower and observe how 

it differs from that of the latter species. 

2. Examine the flower under a lens and observe 

a. The conspicuous nectary. (Abundant nectar may 

also be found in some flowers.) 

b. The surface of the ovary. Can you suggest more 

than one use of the hooked bristles with which 
it is covered ? 

3. Observe, if practicable, the way in which pollination 

takes place. 1 

III. A study of the cultivated Fuchsia may be made at 
any time during several months of the year, and if more 
convenient may be taken as the type instead of the even- 
ing primrose. 

IV. Compare your observations of the various members 
of the family that you have obtained for study, and note 
the morphological characters common to them all. 

1 Cf. Miiller, I.e., pp. 266, 267. 



THE PARSLEY FAMILY. 203 



XXXII. THE PARSLEY FAMILY. 
UMBELLIFER^E. 

MATERIAL REQUIRED. 

Harbinger-of -spring, Erigenia bullosa, Nutt., in flower. 

Later in the season, representatives of other genera, such as Osmor- 

rhiza, Heracleum, Pastinaca, Thaspium, Daucus, Cicuta. 
Fruits of fennel, Foeniculum vulgare, Gaertn., dill, Anethum graveolens, L., 

and coriander, Coriandrum sativum, L. (to be procured at the 

drug store). 

HARBINGER-OF-SPRING. Erigenia bullosa, Nutt. 
Distribution and General Characters. 

I. Record what you have noticed as to the habitat of 
this species. Does it appear to be indigenous or intro- 
duced? 

II. With perfect specimens at hand, study the general 
features of the plant, noting particularly 

1. The underground stem. Describe its form and struct- 

ure. As a modified stem how is it to be classi- 
fied? 1 

2. The habit of the plant as regards size, branching, 

and any other feature that appears to be charac- 
teristic. 

3. Leaves. Compare a number of proper foliage leaves 

and describe one that you regard as typical. Notice 

a. The expanded, sheathing petiole. 

b. The extent to which the leaf is compound. 

1 Cf. Gray, Lessons, p. 42 et seq. 



204 STUDY OF COMMON PLANTS. 

e. The uppermost leaves. Those subtending a group 
of inflorescences constitute an involucre, those 
subtending each separate inflorescence an in- 
volucel. Do the leaves of involucre and involu- 
cel differ in any important particular from the 
lower leaves ? 
4. The character of the inflorescence, and the grouping 
of several inflorescences to form a compound umbel. 

Flower. 

I. Examine different flowers until you are satisfied as to 
what parts are present. Note the essential facts of form, 
number, position, etc. 

II. Write a description, and indicate all the points in 
which this differs from a " typical flower." 

Note. — In this family the inflorescence and flowers are particularly 
characteristic ; it is important, therefore, that their distinctive features 
should be impressed on the mind before proceeding farther. 

Fruit. 

Fully mature specimens are indispensable in studying 
the fruit of any member of this family ; accordingly, 
instead of waiting for the Erigenia to ripen, it will be con- 
venient to take commercial specimens of fennel, coriander, 
and dill, which will serve as good representatives of the 
fruits of umbelliferous plants. Moreover, by studying 
several kinds, instead of one, we shall gain a clearer im- 
pression of their really characteristic features. 

I. Observe carefully the external features of the three 
fruits. That of the coriander is globular, fennel is more 
nearly cylindrical, while dill is much flattened. In spite, 
however, of these marked differences, there are a number 
of characters common to all three. Note 



THE PARSLEY FAMILY. 205 

1. The ready splitting of the fruit into two halves, 

mericarps. 

2. The strongly marked longitudinal ribs on the outer 

surface of each mericarp. 

3. The stylopodium, a short conical body in which the 

fruit is prolonged above. 

4. The carpophore, or prolongation of the pedicel ; its 

two thread-like branches each supporting one of 
the mericarps. (Best seen in specimens of fennel 
that have lain in water an hour or two.) 

II. Compare the three fruits more in detail, using a 
good lens for the purpose. Observe 

1. The number and position of the ribs. Begin with 

fennel, in which it is at once seen that each meri- 
carp has five strong ribs, two lateral, one dorsal, 
and two intermediate. How does the dill fruit 
compare in this respect ? 
The coriander fruit differs remarkably from either of 
the preceding. If a mericarp is carefully studied, 
it will be seen to have five primary ribs, corre- 
sponding to those of fennel, but wavy in outline 
and less prominent than four secondary ribs alter- 
nating with them. 

2. Remains of floral envelopes. If uninjured specimens 

are examined, it will be seen that the calyx teeth of 
the coriander are conspicuously present at the apex 
of the fruit. Is this true of the dill and fennel ? 

III. Prepare transverse sections of the mericarps of all 
three species, and examine with the low power of a com- 
pound microscope. In each case it will be necessary to 
take at least two sections, one near the apex of the fruit, 
and one near the middle or lower down. 



206 STUDY OF COMMON PLANTS. 

It will be seen that all three kinds have a relatively 
thick pericarp and abundant, white endosperm, within which 
lies the small embryo, near the apex of the fruit, and con- 
sequently not seen in sections taken lower down. In the 
pericarp are a number of vittse, or oil-tubes. The corian- 
der has two of these in each mericarp lying next to its in- 
ner, or ventral face. In fennel and dill, in addition to 
these two, there are four more vittae alternating with the 
ribs of the outer, or dorsal face. 

Draw in outline, representing accurately the position of 
ribs and vittse. Letters and guiding lines will conduce to 
clearness. 

IV. Write a complete description of the three fruits, 
taking care to distinguish the characters common to all, 
from those that are only of specific or generic value. 

RELATIONSHIP. 

Later in the season many other species of umbellifers 
that will serve for comparative study are easily obtained. 
Thaspium, or some other common genus, may be substi- 
tuted for Erigenia if found more convenient. As the 
study is continued it will be apparent that the external 
characters to which attention has already been directed, 
although variously modified, are constantly repeated in 
nearly all the genera. The hollow stem, compound leaves 
with inflated petioles, flowers in umbels, and the very 
marked and distinctive features of flowers and fruit occur 
over and over again, sometimes in connection with specific 
characters by which a given plant is easily identified, some- 
times with these characters so far wanting that identifica- 
tion becomes extremely difficult. All in all, the family is 
one of the best marked groups in the vegetable kingdom. 
It includes about thirteen hundred species, distributed 



THE PARSLEY FAMILY. 207 

chiefly over the temperate regions of the globe. They are 
remarkable for their widely different active properties, a 
considerable number being edible, a large proportion pleas- 
antly (or unpleasantly) aromatic, and a comparatively small 
number poisonous. It is a curious fact that while very 
largely dependent upon insects for fertilization, the flowers 
of umbellifers attract, as a rule, a very common lot of visit- 
ors such as " short-lipped flies, beetles, and other short- 
lipped insects in immense variety." a Numbers, rather 
than quality, has become the rule, and while the family 
has held its own, and has even established a claim to be 
considered one of the dominant natural orders, it is one 
of the least attractive. 

The best preparation for the further study of this rather 
difficult family will be made by getting together a collec- 
tion of ripe fruits, especially those occurring in commerce, 
and becoming thoroughly familiar with their anatomical 
structure. 

Useful directions for collecting and other needed sug- 
gestions are given by Coulter and Rose, in their Revision 
of North American Umbelliferce? 

SPECIAL STUDIES. 

I. Morphology of the " tuber" of Erigenia bullosa. 

A critical botanist writes : " Is it really a stem? 
Who ever examined it ? It appears to me to be 
half hypocotyl, and the other half a root." 
II. The terminal, colored flower of Baucus Carota. 

1 Miiller, Fertilization of Flowers, p. 287. 

2 Separate monograph. Issued by the Herbarium of Wabash College, 
December, 1888. 



208 STUDY OF COMMON PLANTS. 



XXXIII. THE MILKWEED FAMILY. 
ASCLEPIADACE^E. 

MATERIAL REQUIRED. 

Flowers of Asclepias Cornuti, Decaisne. Alcoholic specimens will 
serve if fresh ones are not to be had, but there is an advantage 
in having a supply of both. 

MILKWEED. Asclepias Cornuti, Decaisne. 
Flowers. 

Our study of the milkweed will be restricted to the 
flowers, which present an extraordinary mechanism for 
securing cross-fertilization through the agency of insects. 
They are borne in a conspicuous umbel and attract numer- 
ous visitors, particularly bees, wasps, and flies. Both the 
odor and color are attractive, and there is an abundant 
supply of nectar. The plant is absolutely dependent on 
insects for fertilization. 

Observe first the form and position of the floral envel- 
opes. They are reflexed and covered on their lower 
surface with short, woolly hairs. (This is contrary to 
the general rule noticed by Kerner, Floivers and their Un- 
hidden Guests, that plants protected by milky juice have 
smooth leaves, and are without any other appliances for 
the protection of their flowers from crawling animals.) 

The crown is the most conspicuous part of the flower. 
It consists of five hollow bodies, cuculli, each of which has 
an incurved horn projecting from its opening. 



THE MILKWEED FAMILY. 209 

There are five anthers placed close together, each ter- 
minating in a membranous appendage that projects over 
the thickened stigma disk. 

The anthers are separated from each other laterally by 
a deep, vertical slit, bordered on either side by a thin 
triangular process, the anther wing. At the upper ex- 
tremity of the slit is a minute, black body, corpusculum, 
which, when removed by a needle, is found to be con- 
nected by means of a delicate, curved band on either side, 
with a flattened, yellow, and waxy pollen-mass, pollinium. 
Longitudinal swellings on the outside of each anther indi- 
cate the position of the pollinia before their removal. 

Each of the slits already described is continuous within 
with the stigmatic chamber, into which the pollen must be 
introduced in order that fertilization may take place. It 
is obvious that this cannot happen unless the pollinia are 
removed from the anthers, and brought into the stigmatic 
chambers by some external agency. 

This is accomplished by bees and other insects that visit 
the flowers for honey. 1 Alighting on the umbel the insect 
easily gets its foot caught in the lower part of one of the 
slits, and in attempting to withdraw it, one of the claws 
is guided into the notch in the lower end of the corpus- 
culum. With a strong pull, the latter is removed from its 
place, and the insect carries away with it the two pollinia, 
which by the twisting of the delicate bands, retinacula, 
that connect them with the corpusculum, are now brought 
into such a position as to be readily introduced into 
the slit leading to the stigmatic chamber of some other 
flower. If this has been done, and the insect is strong 
enough, it frees itself by a vigorous pull, breaking the 

1 Hildebrand and Muller have given a full account of the process, the 
latter writer with illustrations. Fertilization of Flowers, p. 396 et seq. 



210 STUDY OF COMMON PLANTS. 

retinacula, and leaving the pollen masses in the stigmatic 
chamber, while it proceeds to other flowers and continues 
gathering honey. 

Weaker insects are frequently unable to break the 
retinacula. Flies may often be seen making unavailing 
efforts to extricate themselves, and honey-bees are not 
infrequently found that have been caught in the same 
way, and have died after prolonged struggles to get free. 

By means of the preceding description, accompanied by 
careful observation at each step, the student will be in a 
position to study the entire mechanism to advantage. He 
should now go over the whole independently, until every 
part of the flower is perfectly familiar. The study of 
external structure should be followed by a comparison 
of cross and longitudinal sections (best made from alco- 
holic material), with sketches to show the parts and their 
relations to each other. 

Several hours will be required to do this properly. 
Miiller's drawings may be consulted, but they are less 
easily understood than the flower itself. Nothing can 
possibly take the place of direct, personal, and long-con- 
tinued study of the object under investigation. Further, 
it is very desirable that the pupil should not only under- 
stand the mechanism, but that he should also see it in 
operation. A few days in summer spent in watching the 
flowers of the milkweed, as the visitors come and go, will 
give full opportunity for this. 



RELATIONSHIP. 

The Asclepiadacese constitute a large and very remark- 
able family of plants, including about thirteen hundred 
species, which are largely tropical, although many repre- 



THE MILKWEED FAMILY. 211 

sentatives occur in the temperate regions of both hemi- 
spheres. The)' are chiefly interesting for the extraordinary 
structural modifications of their flowers, which " rival the 
orchids, if not in the variety of their forms, at least in 
their complexity and their perfect adaptation to insect 
visitors." A study of the steps by which this gradually 
increasing complexity of structure has been attained is 
of the highest interest. The student should carefully com- 
pare the flowers of other genera of Asclepiadacese, and 
such representatives of related families as Apocynum, 
Vinca, and others. 

SPECIAL STUDIES. 

I. It is found that only a very small proportion of the 
flowers in an umbel set fruits. Why is this? and 
are those flowers which do not set fruits of any 
value to the plant ? 
II. Minute structure of pollinia and retinacula. 

III. Morphology of the cuculli. 

IV. Development of the flower. 

V. Protective appliances in this family. 



212 STUDY OF COMMON PLANTS. 



XXXIV. THE BORAGE FAMILY. 
BORRAGINACE^:. 

MATERIAL REQUIRED. 

Common hound's-tongue, Cynoglossum officinale, L., in flower. 

Similar specimens of any of the following genera : Echinospermum, 
Mertensia, Lithospermum, Symphytum, Heliotropium, Myosotis. 
Cultivated species of some of these, as forget-me-not and helio- 
trope, will serve a good purpose. 

HOUND'S-TONGUE. Cynoglossum officinale, L. 
Distribution and General Characters. 

I. This species is described as an introduced weed. Do 
its habits confirm this statement? 

II. Examine the plant with reference to general feat- 
ures. Note its coarse aspect, hairy surface, and dis- 
agreeable odor. 

Inflorescence. 

The inflorescence is characteristic and should be criti- 
cally studied, as it is of a form that appears in many rep- 
resentatives of this family. 

I. Notice first the order of development of the flowers. 
The lowest have already formed their fruits ; higher up 
are the open flowers, and at the apex are the unopened 
flower buds. 

II. The inflorescence is apparently a one-sided raceme. 
Is it really so ? Notice the position of an open flower. Is 
it terminal or lateral ? 



THE BORAGE FAMILY. 213 

III. Compare a number of inflorescences with reference 
to the occurrence of bracts. Read Gray, Structural Botany, 
pp. 153-155. 

IV. If they can be obtained at the same time, compare 
the inflorescence of other representatives of the Borragi- 
nacese, such as puccoon and forget-me-not, with that of 
hound's-tongue. Do they agree essentially in the arrange- 
ment of flowers ? 

Flower. 

I. Note first the numerical plan of the flower. Is the 
number five maintained throughout ? 

II. Observe the peculiar structure of the corolla, par- 
ticularly the conspicuous folds or scales arching over the 
essential organs. Is the flower perfectly regular? 

III. Taking a recently opened flower, make a longi- 
tudinal section so as to show the precise relation of all the 
parts. Draw. 

Does the position of stigma and anthers, and the mode 
of dehiscence of the latter, afford any indication as to the 
way in which pollination is effected ? 

IV. Examine the ovary, noting the number of its divis- 
ions, and their form and position. 

Fruit. 

I. Study the fruit in different stages of development, 
taking flowers of different ages for the purpose. Observe 

1. Its rapid increase in size. 

2. The formation of peculiar barbed appendages, thickly 

covering its surface. 
II. Make longitudinal sections of young fruits so as to 
show the form and position of the seed. Compare with 
similar sections of older fruits. 



214 STUDY OF COMMON PLANTS. 



RELATIONSHIP. 



Compare with this species as many others of the same 
family as can be obtained. Note especially 

I. Any general external characters in which they agree. 

II. The inflorescence, which in this family presents very 
interesting peculiarities. 

III. The structure of the flowers, differing in details in 
the different genera, but showing marked agreement in 
plan. 

IV. The characteristic fruit. 

V. Structure and position of the seeds. 

Write a brief summary of the features that you consider 
characteristic of the family. 

The Borraginaceso include about twelve hundred species, 
widely distributed throughout the world. A number of 
ornamental ones are common in cultivation. Some have 
been employed in medicine, and the curious doctrine of 
signatures is still called to mind by such names as lung- 
wort and stonewort. The marked variety of external 
appearance, in connection with great persistence of essen- 
tial characters, as seen, for example, by comparison of the 
exquisitely beautiful and fragrant heliotrope with the 
coarse and rank hound's-tongue, is interesting as suggest- 
ing how widely the different genera have diverged in 
externals from earlier forms, while still retaining their 
most deeply seated ancestral traits. 

The student will do well to make a special study of the 
inflorescence as it presents itself in various members of 
the family, and in the same connection review the whole 
subject of floral arrangement as presented by Gray, Les- 
sons, Sec. VIII, or Structural Botany, Chap. V. 



THE MINT FAMILY. 215 



XXXV. THE MINT FAMILY. LABIATE. 

MATERIAL REQUIRED. 

Specimens of ground-ivy, Nepeta Glecho?na, Benth., in flower. 
Similar specimens belonging to different genera of the Mint family, 
as they can be obtained. See list below. 

GROUND-IVY. Nepeta Glechama, Benth. 

Distribution. 

As in previous studies, notice the habitat and consider 
the evidence as to whether this is an introduced or indige- 
nous species. Gray, in the Manual, says " naturalized 
from Europe." What is meant by this? 

General Characters. 

I. Observe first the most obvious characters, among 
them the following : 

1. The habit of the plant, its stem creeping and taking 

root at short intervals. Describe the root system. 

2. The characteristic odor. 

3. The shape of the stem and arrangement, of the 

leaves. 

Xote. — The aromatic properties, square stem, and opposite 
leaves are characteristic not only of this species but of the whole 
family to which it belongs. 

4. The relation of leaves and stem. Note particularly 

the ridges connecting the bases of each pair of 
petioles, and their chevaux-de-frise of bristly 



216 STUDY OF COMMON PLANTS. 

hairs. Which way are the latter directed ? What 
do you infer as to their use ? 
5. Structural features of the leaves. Describe their 
form and venation. With a good lens examine 
closely the surface and margin. Are they smooth 
or rough ? 

II. Study the plant throughout with reference to its 
various means of protection and their efficiency. 

Inflorescence. 

I. The flowers are in small axillary clusters. How 
many in each group ? In what order do they open ? Is 
this order constant? Classify the inflorescence, giving its 
appropriate name. 1 

II. Are there any arrangements, in addition to those 
already noticed, for the protection of the fkwer? 

Flower. 

I. Study critically the plan of the flower. How many 
calyx-teeth are there ? How many lobes of the corolla ? 

Remove the corolla with a pair of fine forceps, and lay 
it open by making a longitudinal slit its entire length, 
passing through the middle of the lower lip. Fasten it 
on a flat piece of cork with needles, so as to fully expose 
the stamens, and examine under a dissecting microscope. 
One of the stamens has been suppressed. Which ? Notice 
the insertion of the style, the peculiar form of the ovary, 
and the nectaiy surrounding its base. 

II. Taking flowers of different ages, observe the fruit 
in its various stages of development. How many carpels 
are there ? 2 

1 Cf. Gray, Structural Botany, p. 151. 

2 Cf. Gray, Structural Botany, p. 296 ; Luerssen, Botanik, p. 1014. 



THE MINT FAMILY. 217 

III. Construct a diagram of the flower. Consult Eichler, 
Bliithendiagramme, for diagrams and theoretical discussion 
of the morphology of the flower of the Labiatae. 

IV. Examine the flower with reference to the way in 
which fertilization is accomplished. 

1. Notice the spots and lines on the lower lip of the 

corolla. Examine different specimens and ascer- 
tain whether they are constant in position. Are 
they placed so as to serve as path-pointers ? 

2. Using a needle or bristle, imitate the action of an 

insect inserting its proboscis so as to extract the 
nectar. Would it be likely to come in contact 
with anthers or stigma, or both ? 

3. If practicable, examine flowers from different locali- 

ties, and compare them as to size, position of the 
anthers, and other features. 1 

4. Nepeta is reckoned by Miiller among the genera in 

which, for at least some of the species, self-fertili- 
zation has become impossible. Does this appear 
to be the case with Nepeta Crleehoma ? 

V. Compare, if they can be obtained, the highly modi- 
fied flowers of Salvia, either those of the common sage, or 
of species cultivated in conservatories. 2 

RELATIONSHIP. 

Examine as many of the following species as practicable, 
comparing them with ground-ivy, and noting all common 
characters. 

Catnip, Nepeta Gataria, L. 

1 Cf. Botanical Gazette, I, p. 41, II, p. 118 ; Miiller, Fertilization of 
Flowers, p. 484. 

2 Cf. Sachs, Physiology of Plants, p. 794 ; Miiller, he., p. 477 etseq. 



218 STUDY OF COMMON PLANTS. 

Wood-sage, Teucrium Canadense, L. 
Richweed, Collinsonia Canadensis, L. 
Spearmint, Mentha viridis, L. 
Wild mint, Mentha Canadensis, L. 
Wild bergamot, Monarda fistidosa, L. 
Skullcap, Scutellaria galericulata, L. 
Motherwort, Leonurus Cardiaca, L. 
Dead-nettle, Lamium maculatum, L. 
Cultivated species of Salvia. 

Notwithstanding the fact that the Labiatse include some 
twenty-six hundred species scattered over the entire globe, 
they constitute a very natural group of plants ; that is, cer- 
tain strongly marked characters are so uniformly present 
that it would almost seem, as some botanical writers have 
suggested, that all the species might be placed in one great 
genus. Accordingly the distinction of genera in this 
family becomes a difficult task. The modifications of the 
floral structures in those species that have become most 
dependent on the agency of' insects for fertilization are 
peculiarly interesting. The student may profitably devote 
considerable time to the comparison of the various species 
of Salvia, for example, with each other and with simpler 
forms. Another interesting subject of investigation, and 
one throwing additional light on the relationship of groups 
that apparently have but little in common, is the develop- 
mental history of the fruit, which is essentially the same 
in this family as in the Boraginacese. 



THE NIGHTSHADE FAMILY. 219 



XXXVI. THE NIGHTSHADE FAMILY. 
SOLANACE^E. 

MATERIAL REQUIRED. 

The cultivated potato in flower. The tomato may be substituted. 

Specimens o£ matrimony-vine, Lycium vulgare, Dunal, in flower, and 
similar specimens of ground-cherry, Physalis pubescens, L., bitter- 
sweet, Solarium Dulcamara, L., or other easily procurable repre- 
sentatives of the family. 

POTATO. Solarium tuberosum, 
Distribution and General Characters. 

The common potato is indigenous to a portion of the 
coast region of western South America. It has been 
widely cultivated in the northern hemisphere for more 
than three hundred years, apparently with little specific 
change, there having been no inducement to artificial 
selection of any other part than the tuber, which, however, 
presents many, often striking, varieties. 1 

In examining the cultivated plant, study its habit, not- 
ing the peculiarities of stem and leaves, and the character- 
istic odor. 

Inflorescence. 

Examine a number of specimens. Do they agree in the 
character of the inflorescence ? Describe this and draw a 
diagram showing the position of the flowers and their 
order of development. 

1 Cf. De Candolle, Origin of Cultivated Plants, p. 45 et seq. 



220 STUDY OF COMMON PLANTS. 

See if you can find a description of this kind of inflores- 
cence in any of the books of reference. Does it correspond 
with that of any other family that you have studied ? 

Flower. 

I. Study the parts of the flower in order and describe 
them. Note particularly 

1. The plan of the flower and whether it is strictly 

regular or not. 

2. The extent to which coalescence has taken place. 1 

3. Whether there is adnation of any parts. 

4. Form of calyx and corolla. 

5. Structure, position, and insertion of the stamens, and 

their mode of dehiscence. 

6. Number of carpels composing the ovary. State the 

evidence on which you have determined this. 

II. Construct a diagram. 

III. Determine whether there are any arrangements 
favoring cross-fertilization, and whether self-fertilization 
is possible. 2 

Note the persistence, for at least several hundred years, 
of structures that under present circumstances are of little, 
if any, use to the plant, but which if it were neglected by 
man and allowed to run wild, might again be needed. 

RELATIONSHIP. 

I. With the potato compare other species of the same 
genus, as far as these are procurable, also representatives of 
other genera as Lycopersicum, Physalis, Nicandra, Lyeium, 

1 Cf. Gray, Structural Botany, p. 179. 

2 Cf . Mullcr, Fertilization of Flowers, p. 425. 



THE NIGHTSHADE FAMILY. 221 

and Petunia. The last two are widely cultivated, and 
their flowers may be had for weeks together. Attention 
should be directed to 

I. Such general external features as the plants possess 

in common. Between certain species and genera 
this likeness in general characters is very striking, 
in other cases it is not apparent. 

% Active properties, manifested in part by odor and 
taste. 

3. Structure of flower and fruit. 

4. Structure of seeds. The seeds of different plants of 

this family exhibit great likeness of form and 
structure, as may be seen by comparing longitu- 
dinal sections of those of tomato, egg-plant, 
stramonium, etc. It is very desirable that the 
student should make an extended and critical 
comparison of the seeds of as many different 
species as possible. This should be assigned as 
a special study, and time given for a thorough 
piece of work. 

II. Write a summary of the characters in which all the 
species examined agree. 

III. Compare the characters of the Solanacese with those 
of any other families that you remember as showing resem- 
blances to them. If you have already studied any of the 
Scrophulariacese point out the best characters by which 
the two families are to be distinguished. 

In the study of every family, comparisons of this kind 
should be made as fast as the necessary data are in hand. 
In most cases the relationships of families among them- 
selves are by no means as satisfactorily made out as could 
be desired, but that is no reason for not studying them. 



222 STUDY OF COMMON PLANTS. 

The Solanaceae include over twelve hundred species, 
chiefly tropical and sub-tropical, some representatives, 
however, being widely cultivated in temperate regions. 
Many of them possess strongly narcotic and poisonous 
properties, as the names deadly nightshade, henbane, etc., 
indicate. A few are much employed in medicine. The 
potato is the most useful, the tobacco plant the most 
harmful member of the family. Morphologically this 
group of plants is of interest in its affinities, more or less 
distinctly marked, with several conspicuous families, the 
Scrophulariaceee and Convolvulacese among them. Physi- 
ologically it offers comparatively little of special impor- 
tance, although some species exhibit interesting adaptations 
for insuring fertilization. 



THE F1GWOHT FAMILY. 223 



XXXVII. THE FIGWORT FAMILY. 
SCROPHULARIACE^:. 

MATERIAL REQUIRED. 

Butter-and-eggs, Linaria vulgaris, Mill., in flower. 
Common species of any of the genera named below. 

BUTTER-AND-EGGS. Linaria vulgaris, Mill. 
Distribution. 

In what situations have you seen the plant growing? 
Have you made any observations as to its natural range ? 
Is there anything in its habits that affords evidence as to 
whether it is indigenous or introduced ? 

General Characters. 

I. This species is perennial. How is the fact ascer- 
tained? 

II. Describe the underground portion of the plant. 
The stem and leaves. 

III. Is there anything about it that secures protection 
from grazing animals ? 

Inflorescence. 

Character and kind of inflorescence. Notice the posi- 
tion of the individual flowers. Do they all face outward? 
Do the position of the flowers and the order of their 
development present any advantages ? 



224 STUDY OF COMMON PLANTS. 

Flower. 

I. Study the plan of the flower. What is the original 
numerical plan as indicated by the floral envelopes? Is 
this plan apparent in the andrcecium ? In the gynsecium ? 
How many perfectly developed stamens are there? See 
if you can find traces of another one. If so, how does it 
compare with the rest ? How many carpels compose the 
pistil? On what evidence is this determined? 

II. Construct a diagram of the flower. If you find a 
trace of a fifth stamen, mark its place with an x* 

III. Examine a transverse section of an ovary from 
which the corolla has fallen, and notice the arrangement 
of the ovules, and the position and form of the placentae. 
In a still older ovary observe the form and structure of 
a young seed. 

IV. When the capsules are ripe study their structure 
and mode of dehiscence. 

V. Study carefully the adaptations for securing fertili- 
zation by the agency of insects. Begin with the corolla 
and note 

1. Its bilabiate form. 

2. The conspicuous palate and its color as compared 

with the rest of the corolla. 

3. The spur. Where is the nectar? Is it easily acces- 

sible to all sorts of visitors ? Imitate the action 
of a bee in gathering honey. Depress the lower 
lip hj pushing down the palate with a needle. 
Are there any path-pointers ? Notice the position 
of anthers and stigma. 

If possible, watch a bee visiting a plant, and observe 
the mutual relations of insect and flower. 



THE FlftWOHT FAMILY. 225 

This plant has been widely introduced into the United 
States, and, notwithstanding its botanical interest, is a 
pernicious weed, difficult to eradicate. Aside from repro- 
duction by seed, it persistently maintains itself by means 
of its rhizomes, each of which sends up several or many 
aerial shoots. The unpleasant odor and taste of the 
plant render it distasteful to grazing animals, so that 
it is efficiently protected by its own disagreeable prop- 
erties. 

The adaptations for securing cross-fertilization by the 
agency of insects are striking, and, for the most part, 
easily understood. The flowers are rendered conspicuous 
by massing in a crowded raceme, and face outward, so as 
to be immediately accessible to flying insects, while the 
orange-colored palate, with its smooth median groove on 
the inner side, directs visitors at once to the nectar col- 
lected in the spur. The anthers and stigma are so dis- 
posed as to come in contact with the head and back of 
the insect (commonly a bee), as it depresses the palate 
and inserts its long proboscis into the spur. While thus 
accessible to large insects with a long proboscis, the nectar 
is protected from unbidden guests by the palate, that com- 
pletely closes the throat of the flow T er, and springs back 
to its place when the force by which it is depressed ceases 
to act. It is further protected by its position, being out 
of the reach of insects with a short proboscis that may 
in some way have effected an entrance into the flower. 

The mechanical arrangements for the dissemination of 
the seeds are also of interest. The hygroscopic action of 
the capsules is readily shown by placing them when dry 
in water. In less than a minute the teeth at the apex 
begin to bend inwards, and in a short time the capsule is 
tightly closed, opening again when it has been thoroughly 



226 STUDY OF COMMON PLANTS. 

dried. In this way the seeds are scattered when the 
weather is most favorable for their being conveyed to 
some distance. On the whole, the plant with its simple 
but effective means of protection, persistent subterranean 
stems, admirable adaptations for cross-fertilization, and 
numerous seeds with special arrangements for dissemi- 
nation, is exceedingly well adapted to survive in the 
struggle for existence. 

RELATIONSHIP. 

I. Compare several of the following plants with the 
species just studied, directing attention particularly, 
though not exclusively, to the flowers. (Some of these 
that bloom earlier than the Linaria, as the wood-betony, 
may be studied before the latter if more convenient.) 

Wood-betony, Pedicularis Canadensis, L. 
Painted-cup, Castilleia coccinea, Spreng. 
Beard-tongue, Pentstemon pubescens, Solander. 
Turtle-head, Chelone glabra, L. 
Monkey-flower, Mimulus ringens, L. 
Various species of Veronica. 

Some cultivated species also may be used such as 
" Kenil worth ivy," Linaria Cymbalaria, Mill. 
Snapdragon, Antirrhinum majus, L. 
Foxglove, Digitalis purpurea, L. . 

How do these compare as regards 

1. Plan of the flower ? 

2. Shape of corolla ? 

3. Number of stamens ? 

4. Structure of ovary ? 

5. Number and position of seeds ? 



THE FIGWORT FAMILY. 227 

II. State concisely, and in general terms, what charac- 
ters you have found to be common to all the species 
studied. 

There is evidence that the Scrophulariaceae are an old 
family of plants, and one that may fairly be reckoned to 
have gained a place among the dominant groups. There 
are nearly two thousand species distributed over the entire 
globe. While well marked as regards family characters, 
the different genera and species exhibit very wide diver- 
gence of structure, often associated with peculiarities of 
color that stand in evident relation to the insects on which 
they have come to depend. A considerable number have 
entirely lost the capacity for self-fertilization, and the 
mechanical arrangements are in some cases so complicated 
as to be difficult of explanation. The gradation of forms 
from comparatively simple ones to others that show 
remarkable adaptations to highly specialized insects, offers 
a peculiarly interesting study of developmental history. 1 

SPECIAL STUDIES. 

I. Morphology of the flower of the Scrophulariaceae. 
II. Peloria in this family and its significance. 

III. Comparison of mechanisms by which fertilization is 

effected in different genera of Scrophulariacese. 

IV. Exclusion of unbidden guests as accomplished in 

Pentstemon and other genera. 

V. The genus Veronica. A comparison of different 
species of the genus, and of the genus itself with 
other representatives of the family. 
1 Cf. Miiller, Fertilization of Flowers, pp. 429-465. 



228 STUDY OF COMMON PLANTS. 



XXXVIII. THE HONEYSUCKLE FAMILY. 
CAPRIFOLIACE^E. 

MATERIAL REQUIRED. 

Common elder, Sambucus Canadensis, L., in flower. Other specimens 
of the same species, with the fruit partially developed. Species 
of Viburnum, coming earlier in the season, may be substituted. 

Any of the indigenous species of Lonicera, Diervilla, Symphoricarpus, 
Linnsea, and Triosteum that are procurable. 

COMMON ELDER. Sambucus Canadensis, L. 

Distribution. 

In what situations have you observed the plant growing ? 
Is it indigenous ? 

General Characters. 

I. Record what you have noticed as to its mode of 
growth. Is its habit that of a shrub or of a tree ? 

II. Mode of branching. Differences observed in differ- 
ent specimens. 

III. Do the stems exhibit any peculiarities of form, 
structure, or surface markings? If so, describe in detail. 

Note. — The lenticels are generally a conspicuous feature. For an ac- 
count of these, see Strasburger and Hillhouse, Practical Botany, pp. 153, 
154. 

IV. Describe the leaves. Note variations. 



THE HONEYSUCKLE FAMILY. 229 

Inflorescence. 

I. Observe the number and position of the main 
branches. Compare specimens until the normal arrange- 
ment is clearly understood. 

II. Ascertain the order of development of the flowers. 
Take a small division of the inflorescence, to avoid confu- 
sion, and represent it on paper diagrammatically. 1 

III. Classify the inflorescence. 2 Does such an arrange- 
ment of flowers present any physiological advantages ? 

Flower and Fruit. 

I. What is the numerical plan of the flower ? Is this 
constant in all the specimens ? Is it exhibited in all the 
whorls ? 

II. Note the relation of the different whorls to each 
other. Is the ovary superior or inferior ? Where are the 
stamens attached ? 

III. Does the relative position of anthers and stigma 
favor cross- or self-fertilization, or both ? 

IV. Make transverse sections of a number of immature 
fruits. Are they all alike ? Draw a section that you con- 
sider typical. Compare the ripe fruits, if they are to be 
had, and note the changes that have taken place. Describe 
and classify the fruit. 

RELATIONSHIP. 

The relationship of the common elder must necessarily 
be made a subject of special study rather than a piece of 
class work, since the indigenous species of Caprifoliacese 

1 Cf. Bessey, Botany, pp. 138, 139. 

2 Cf. Gray, Structural Botany, pp. 151, 152. 



230 STUDY OF COMMON PLANTS. 

flower, for the most part, at widely different times, and 
some of the genera exhibit among themselves such marked 
structural differences as to obscure, except to a trained 
eye, the common family characters. The contrast between 
the simple, open flowers of the elder and the extremely 
elongated corolla of species of Lonicera that have become 
adapted to the visits of night-flying moths, is a striking 
example. The student who wishes to familiarize himself 
with this family, which presents many interesting features, 
will find in the course of spring and summer enough 
indigenous species of the genera named above to enable 
him to make a fairly extended comparative study. The 
clue to the wide divergence of form, and the remarkable 
series of colors exhibited by flowers of the different genera, 
is apparently found in progressive adaptation to different 
insect visitors. 1 

Another remarkable feature is the great difference of 
habit exhibited by different members of the family, as 
seen, for example, in a comparison of the slender, trailing 
Linnsea with the coarse, upright Triosteum, or the climb- 
ing species of Lonicera with the shrubs or trees of the 
genera Sambucus and Viburnum. Even within the limits 
of a single genus, as in the case of Lonicera and Viburnum, 
wide differences of structure and habit present themselves, 
affording an opportunity to observe adaptations that ap- 
pear to have been acquired within comparatively recent 
times. 

1 Cf. Miiller, Fertilization of Floivers, p. 299. 



THE GOURD FAMILY. 231 



XXXIX. THE GOURD FAMILY. 
CUCURBITACE^E. 

MATERIAL REQUIRED. 

The common cucumber, Cucumis sativus, L., in flower. 1 
Similar specimens of squash, melon, wild cucumber or gourd. 
Seeds of pumpkin, melon, and various other cucurbits. 

CUCUMBER. Cucumis sativus, L. 
Distribution. 

The cucumber has been widely cultivated from an early 
date, and presents a remarkable case of the persistence of 
specific characters for an indefinite period. According to 
De Canclolle, it has been cultivated in India no less than 
three thousand years, yet its wild form found at the foot 
of the Himalayas has stems, leaves, and flowers that are 
" exactly those of Cucumis sativus" 2 

General Characters. 

I. Note first the habit of the plant as regards position 
and direction of growth. Is it capable of supporting itself 
in an erect position ? How do young specimens compare 
with older ones in this respect? 

II. Observe the leaf arrangement. 

III. Is the plant protected in any way? Examine the 

1 Well-formed plants, with flowers and young fruits, are easily ob- 
tained by sowing the seeds in flower-pots a few weeks before the speci- 
mens are wanted. 

2 Origin of Cultivated Plants, pp. 264-266. 



232 STUDY OF COMMON PLANTS. 

surface of stems, leaves, flowers, and fruit, first with the 
naked eye, and then with a good lens. Imagine a soft- 
bodied animal attempting to crawl up to the leaves or 
flowers. Which parts are best protected ? 

Tendrils. 

I. Study carefully the tendrils, noting particularly their 
origin, form, and mode of grasping a support. How do 
they compare in their subsequent behavior with those of 
bryony, described by Sachs ? * 

II. Rub one of the young tendrils and watch it for a 
few minutes. Is there any movement? Does it make 
any difference whether the concave or convex side is 
rubbed ? 2 

III. Watch a vigorous specimen long enough to observe 
the spontaneous movements of its tendrils. 

Inflorescence and Flowers. 

I. How many flowers compose the inflorescence? Are 
they all alike ? Compare those in the axils of the lower 
leaves with the ones produced higher up. Is this species 
monoecious or dioecious? 3 

II. Examine carefully the stamens, noting the form 
and structure of the anthers and their peculiar mode of 
cohesion. 4 

III. How many stigmas are there? Examine their sur- 
face with a lens. 

IV. Are there any nectaries? How far do the flowers 
of the cucumber agree with those of Bryonia dioica, as 

1 Physiology of Plants, pp. 663, 664. 

2 Cf . Darwin, Climbing Plants, p. 127 et seq. 

3 Cf. Gray, Lessons, p. 85. 

4 Cf. Goebel, Outlines of Classification and Special Morphology, p. 357. 



THE GOURD FAMILY. 233 

described by Miiller ? a Does their structure indicate self- 
or cross-fertilization ? 

V. Examine the ovary of one of the oldest flowers. 
Is there any external indication of the number of carpels? 

Make a transverse section and notice the number of 
cells, the position of the placentae, and the form and direc- 
tion of the ovules. Draw the section in outline. Repre- 
sent by dotted lines the commissural lines of union of the 
carpellary leaves. 2 

RELATIONSHIP. 

Seeds of squash, melon, and many other plants belonging 
to this family, are easily procurable, and afford the means 
of extended and instructive comparative study. Seedlings, 
which may be had in the course of a few days, exhibit 
with remarkable uniformity in the different, genera the 
characteristic contrivance by which the seed-coats are 
ruptured and the cotyledons released. 3 Tendrils of vari- 
ous species, that may be studied anywhere a little later 
in the season, are of 'the greatest interest, morphologically 
as well as physiologically, and in their turn contribute to 
the sum of characteristic features by which this family is 
marked. If all these are carefully studied, as well as the 
flowers and fruits, and due weight is given to every well- 
marked trait, it will be found that the " famity characters" 
include more than the structural details usually given. 
The behavior of the seedlings in breaking through the 
ground, the highly developed tendrils and their mode of 
action, and even the active properties of some of the 

1 Fertilization of Flowers, pp. 268, 269. 

2 Cf. Eichler, Bluthencliagramme, p. 306. 

3 Darwin, Power of Movement in Plants, p. 102. 



234 STUDY OF COMMON PLANTS. 

species are as truly characteristic as various other features 
upon which more emphasis is usually laid. 

The student is recommended to make a special study of 
seeds and seedlings of the Cucurbitacese, and to proceed 
from these, as material and opportunity permit, to the 
characters observable in later stages of growth. 



THE COMPOSITE FAMILY. 235 



XL. THE COMPOSITE FAMILY. COMPOSITE. 

MATERIAL REQUIRED. 

Specimens of the common dandelion in flower, others with the fruits 

in different stages of development. 
Similar specimens of robin 's-plantain, Erigeron bellidifolius, Muhl. (or 

other species of Erigeron), plantain-leaved everlasting, Antennaria 

plantaginifolia, Hook., golden ragwort, Senecio aureus, L. 
Later in the season, yarrow, A chillea Millefolium, L., mayweed, Anthe- 

mis Cotula, DC, oxeye daisy, Chrysanthemum Leucanthemum, L., 

wild lettuce, Lactuca Canadensis, L. 
In the fall, asters, goldenrods, and various species of Bidens, Prenan- 

thes, and other late flowering composites. 

THE DANDELION. Taraxacum officinale, Weber. 
Distribution. 

Where were the specimens gathered? Does the plant 
manifest any choice of locality or surroundings ? Is it an 
indigenous or introduced species ? 

General Characters. 

With a perfect specimen in hand, note the several parts 
of the plant and write a brief description, including an 
account of the form, structure, and apparent duration of 
the root, the stem (so short that the plant is said to be 
acaulescent), the position and form of the leaves, the 
character of the inflorescence and its support, and any 
conspicuous peculiarities, such as taste, color of the latex, 
etc. 



236 STUDY OF COMMON PLANTS. 

Inflorescence. 

I. Observe first the cylindrical hollow stalk (scape) 
by which the head is supported. How do those of older 
specimens compare in length with those of younger ones ? 
Can you suggest any advantage in this ? 1 

II. The head is subtended by an involucre of green, 
leaf-like bracts. 

1. Is there more than one row of bracts? How do the 

outer differ from the inner ones? 

2. Compare the position of the involucre in the early 

morning with that assumed later in the day, and 
finally in the evening ; in clear and rainy weather. 
Do these observations suggest anything as to the 
function of the involucre ? 

III. Taking a well-developed head, not so old but that 
a few of the flowers of the center are still unopened, make 
a longitudinal section. 

1. Observe the disk-like, expanded end of the stalk on 

which the flowers are borne, the receptacle. Is it 
concave or convex ? How does it compare in this 
respect with the oldest receptacles from which the 
seeds have fallen ? Suggest advantages. 

2. Note the order of development of the flowers. Cen- 

tripetal or centrifugal ? 

Flowers. 

These should be studied in position and also separately, 
removing for this purpose several flowers with a pair of 
fine forceps. 

I. Examine a fully developed flower throughout. With 

a good lens observe 

1 In this and some other cases it will be necessary to supplement the 
laboratory exercises by out-of-door observations. 



THE COMPOSITE FAMILY. 237 

1. The seed-like ovary, its form and surface, and. the 

prolongation of its upper end into a short beak, 
which afterwards becomes greatly elongated. 

2. The calyx, with its limb of numerous fine bristles, 

pappus. 

3. The yellow, ligulate corolla. 

4. The stamens inserted on the corolla, epipetalous, 

with their anthers united in a hollow cylinder 
around the style, syngenesious, the latter soon pro- 
jecting beyond them and divided above into two 
♦ slender, recurved, and finally coiled branches. 

(Specimens should be gathered in the morning 
and also in the afternoon.) 

II. Compare successively older, outer flowers with the 
younger ones, approaching finally the unopened flowers at 
the center. Note the different stages of development of 
the flower, particularly of the stamens and pistil. Observe 

1. The way the pollen is pushed out by the style. 

2. The short, stiff hairs on the outer surface of the 

latter. 

3. The papillae on the inner, stigmatic surface of each 

of its branches. (These latter require higher 
magnification in order to be seen clearly.) 

III. Imitate the action of a bee or other insect by 
repeatedly brushing a large number of flowers. Examine 
the stigma before and after the operation. Is there any- 
thing to favor cross-fertilization ? 

Fruit. 

Study next a head in fruit. Compare the hard, seed- 
like achenium with the immature ovary already examined 
and note differences. What arrangements are there for 
the dissemination of the fruits ? 



238 STUDY OF COMMON PLANTS. 

Review your observations and record them precisely. 
I. In writing an account of the flower treat it first from 
the morphological standpoint, including a discussion of 

1. Original plan of the flower, as indicated by notches 

at the end of the corolla and number of stamens. 

2. Relation of calyx and ovary. 

3. Other evidences of modification. 

II. Enumerate the various physiological adaptations 
such as 

1. Protective arrangements. , 

2. Adaptations for securing fertilization. 1 

3. Means of dissemination of seeds. 

ROBIN'S-PLANTAIN. Erigeron bellidifolius, Muhl. 

Distribution. 

Where have you noticed the plant growing most abun- 
dantly ? Does it appear to be indigenous or introduced ? 

General Characters. 

Describe the root, stem, and leaves. Note means of pro- 
tection, if such exist. 2 It is said to produce " offsets." 
Verify the statement. 

Inflorescence and Flowers. 

I. Compare the heads with those of the dandelion. 
What are the most striking differences ? 

II. Make a longitudinal section and examine in their 
natural position, and also separately, the purple ray flowers, 
and the small, yellow disk flowers. The ray flowers are 

1 Cf. Lubbock, British Wild Flowers in Belation to Insects, p. Ill 
et seq. ; Miiller, Fertilization of Floioers, pp. 316-318, 359. 

2 Cf. Kerner, Flowers and their Unbidden Guests, Chap. IV. 



THE COMPOSITE FAMILY. 239 

ligulate, like those of the dandelion ; the disk flowers are 
tubular. 

Do both ray and disk flowers have stamens and pistil? 
Are both fertile ? 

III. In older heads examine the achenia, and observe 
their form and surface. 

IV. How far do the arrangements for securing fertiliza- 
tion correspond with those observed in the dandelion ? 

V. Compare the flowers of the two plants as regards 
modification from an assumed original form. 

PLANTAIN-LEAVED EVERLASTING. Antennaria 
plantaginifolia, Hook. 

As in preceding cases, note where this plant occurs, and 
record any peculiarities in its mode of growth. Notice 
particularly its habit of spreading by runners. 

It will be observed that there are two sorts of flowering 
heads, on different individuals, one, pistillate, more elon- 
gated and lighter colored than the other, staminate, ones. 

Study critically the flowers of the two different kinds 
of heads. Note all the points in which they are unlike, 
including differences of pappus and corolla, fertility, 
color, size, etc. 

Compare the flowers of this species with those of the 
dandelion and robin's-plantain, noting in each case points 
of similarity and difference. 

RELATIONSHIP. 

A comparative study should be made of as many other 
genera of Composite as practicable. There are so many 
species, ranging in their time of flowering from spring to 



240 STUDY OF COMMON PLANTS. 

late autumn, that there is no difficulty in obtaining abun- 
dant material. With patience and close attention to 
details of structure, there is no reason why the student 
should not become thoroughly familiar with the charac- 
ters of this important and extremely interesting family, 
although the determination of the limits of genera and 
species is often a matter of great difficulty, owing to the 
number of intermediate forms and the tendency to vari- 
ability exhibited by many species. 

When as many species have been studied as the time 
will permit, write a careful summary of the morphological 
characters in which they all agree. This should be accom- 
panied by a resume of their physiological peculiarities, 
especially the arrangements for securing fertilization and 
the dispersal of seeds. 

The Compositse constitute the largest family of flower- 
ing plants, including over one thousand different genera. 
Admirably fitted to survive in the struggle for existence, 
they have become distributed throughout the world, and 
retain tenaciously their dominant position. Some of the 
genera are represented by so many species, and are so 
abundant as to form in their season a characteristic feature 
of the landscape, as is the case, for example, with the 
asters and goldenrods in eastern North America. " The 
numerical preponderance, . . . and extreme abundance of 
many of the species, are due to the concurrence of several 
characters, most of which, singly, or in some degree com- 
bined, we have become acquainted with in other families, 
but never in such happy combinations as in the Com- 
positse." See Miiller's discussion of these points in the 
Fertilization of Flowers, p. 316 et seq. 



REVIEW AND SUMMARY. 241 



REVIEW AND SUMMARY. i 

After such exercises as those outlined in the preceding 
pages, even if only a small number of families have been 
studied, the student can hardly fail to have Threes of 
grasped the conception of degrees of relation- relationship. 
ship, a conception that lies at the very foundation of bio- 
logical science. 2 If we now extend our study farther, and 
compare families with each other, as we have been com- 
paring their genera, we shall find that the principle is 
general, and that families, as well as genera and species, 
show relationships among themselves, falling naturally into 
larger groups to which the term " order " is now commonly 
applied. 3 In some cases these groups are distinctly marked, 
and the close relationship of the families composing them 
is unmistakable, while in others the affinities of a family 
are obscure. In an inquiry of this kind there are neces- 
sarily inherent difficulties, and it must be said frankly, that, 
in the present state of botanical science, it is impossible to 
construct a system that will fully and truthfully represent 
the relationship of families of plants to each other. Never- 
theless it is desirable before proceeding farther to notice 

1 It is assumed that the order recommended on page 96 has been fol- 
lowed, or at least that the student has acquired a reasonably familiar 
acquaintance with the prominent families of flowering plants. 

2 " For myself, there comes from the eighth year memory of an 
awakening to the conscious grasp and knowledge of genus and species. 
I see it yet ... in my lap the shredded petals of almond, plum, and 
the yellow rose of Persia, and in myself sense of a new concept and tool 
for classifying and accumulating knowledge through all life." — Talcott 
Williams, in the Century, January, 1893. 

3 "Natural order" is still employed by many writers as equivalent to 
family, but the usage indicated above is becoming prevalent. 



242 STUDY OF COMMON PLANTS. 

some of the cases in which such affinities are plainly marked. 
A few of these will serve as examples of many others. 

The Cruciferse, as we have seen, are so plainly defined 
by their cruciform, tetradynamous flowers, pungent proper- 
Groups of ties, and characteristic fruits and seeds, that we 
families. naturally think of them as sharply marked off 

from all other families of plants. A number of smaller 
families, however, are manifestly related to them. In one 
of these, the Capparidacese or caper family, the flowers are 
cruciform, the plants often pungent, the pods nearly the 
same as those of the Cruciferse, and the seeds similar; but 
there are certain differences of the embryo and stamens 
that require a separation of the two families, which other- 
wise are nearly identical in their characters. In like man- 
ner the members of the Rosacese, another prominent and 
well-marked family, show such plain affinities with the 
Saxifragacese that the differences by which the two families 
are distinguished from each other seem trivial in compari- 
son with their strong likeness. Again, while the Labiatse, 
with their square stems, opposite leaves, bilabiate flowers, 
and aromatic properties, form a most characteristic group 
of plants, their relationship with the Verbenacese, which 
exhibit a number of characters in common with them, is 
manifest at a glance. In the same way the Asclepiadacese 
and Apocynaceae show a remarkable likeness, and this is 
still more strikingly true of the Liliacese and a number of 
families that form with them another marked group, or 
order. 

These examples are sufficient to illustrate the natural 
grouping of families into orders. Thus, the Labiatse w^ith 
Orders and nine other families constitute the Labiatiflorse, 
higher groups, the Liliaeese with fifteen other families the 
Liliiflorae, and so on. At present botanists recognize some 



REVIEW AND SUMMARY. 243 

thirty orders of dicotyledons, including about one hundred 
and sixty-three families, and seven orders of monocotyle- 
dons with about forty families, while the gymnosperms 
include three orders with thirteen families. 1 The orders 
themselves are associated in higher groups, which in their 
turn make up the great classes just named. 2 

Another fact of prime importance, that cannot well have 
escaped the student's attention, is the gradually increasing 
complexity of structure, particularly of the floral Progressive 
organs, met with as we proceed from more prim- ^Yoraf 10I1S 
itive to more advanced families. Comparing a organs. 
lily, for example, with an orchid, or a buttercup with a 
dandelion, it is plain that the flowers of the higher families 
have undergone very remarkable changes of form and 
structure, although the fundamental plan may still be 
recognized. These changes of structure represent, as a 
rule, progressive adaptation to cross-fertilization through 
the agency of insects. It appears, too, from all we can 
learn of them by comparative study, that these progressive 
modifications have taken place step bj^ step with corres- 
ponding modifications of structure and habit on the part 
of their visitors. The history of such a flower as that of 
the sweet-pea or violet, of the milkweed or daisy, must, if 
this view is correct, reach far back into the past, so far that 
the imagination fails to reproduce the long series of changes 
that have taken place in the succession of intervening 
generations. A glimpse of this history, helpful and satis- 

1 Cf. Luerssen, Botanik, Bd. 2, pp. vii-x. 

2 These groups of a higher order are less satisfactorily denned. Tor an 
attempt at their systematic presentation, see Goebel, Outlines of Classifi- 
cation and Special Morphology, pp. xi, xii. The student will do well to 
remember that all such attempts to represent the affinities of families and 
higher groups involve more or less uncertainty, and that all classifications 
are of necessity provisional. 



244: STUDY OF COMMON PLANTS. 

factory as far as it goes, is given by M tiller in his general 
retrospect at the close of the Fertilization of Flowers, as 
follows : " Insects must operate by selection in the same 
way as do unscientific cultivators among men, who preserve 
the most pleasing or most useful specimens, and reject or 
neglect the others. In both cases, selection in course of 
time brings those variations to perfection which corre- 
spond to the taste or to the needs of the selective agent. 
Different groups of insects, according to their sense of 
taste or color, the length of their tongues, their way of 
movement and their dexterity, have produced various 
odors, colors, and forms of flowers; and insects and flowers 
have progressed together towards perfection." 

Turning to the lower or so-called cryptogamic plants, it 
appears that precisely the same principles hold good. Ferns 
and mosses, quite as plainly as plants higher in 
A progressive the scale, exhibit degrees of relationship. Here, 
series. as e l se where, closely related species fall natu- 

rally into genera, closely related genera into families, and 
these into orders and higher groups. Furthermore, a 
review of these higher groups shows that the vegetable 
kingdom as it exists to-day presents a progressive series, 
rising from such simple plants as Spirogyra, and even more 
primitive forms of the green algse, through the liverworts 
and mosses to the vascular cryptogams, and from these by 
an almost insensible step through Selaginella and its allies 
up to the gymnosperms and flowering plants. It is be- 
lieved by those w T ho have the most extended and critical 
knowledge of plant life that this series corresponds closely 
with the order of development of the vegetable kingdom, 
and, as a matter of fact, it is found that the geological 
record strikingly confirms this view. In earlier geological 
times, beginning with the Silurian Age, marine algae and 



KEVIEW AND SUMMARY. 245 

other cellular cryptogams were the dominant forms of 
plant life. Vascular cryptogams appeared in the Devo- 
nian ; after them came the gymnosperms ; then the mono- 
cotyledons; and finally the different classes of dicotyledons 
attained their present supremacy. 1 

The life history of the flowering plants and higher cryp- 
togams still further confirms the same view, passing as 
they do through successive stages of development that 
repeat in miniature the history of past ages of plant life. 
The fern prothallium in its earlier stages of growth is so 
nearly a filamentous green alga as to be distinguished 
from one by its origin rather than by its structure ; a little 
later it becomes a flat expansion of cells, so like a liver- 
wort as to deceive the inexperienced eye ; and these and 
other phases of their developmental history may still be 
recognized, not only in the gymnosperms, but in the higher 
flowering plants. 

From facts like these, it seems impossible to draw any 
other conclusion than that there has been from the earliest 
appearance of plant life on the globe a slowly 

, , , P • -i , -i • 1 Conclusions. 

progressive development irom simpler to higher 
forms, and that the record of this is still preserved to us 
in the natural groups that form the present vegetation of 
the earth. 

We are to think, then, of the plants we have studied 
and those we have yet to study, as in reality all members of 
one vast and ancient family, some closely, others remotely 
related, some still retaining the simple forms and habits of 
earlier days, and others, through a long course of selection, 
exquisitely adapted to animal structures no less highly 
modified and adapted to them. In this great family, we 

1 Lester F. Ward, Am. Nat., August, 1885. 



246 STUDY OF COMMON PLANTS. 

have learned to distinguish species, genera, families, orders, 
and classes ; but these are simply expressions of so many 
different degrees of relationship that pass insensibly into 
each other, and call for the exercise of clear judgment, 
profound knowledge, and critical attention to details on 
the part of those who attempt to recognize and define 
them. 1 

This is a conception widely different from that which 
supposes " that species, and even genera, are like coin from 
the mint, or bank-notes from the printing press, each with 
its fixed marks and signature, which he that runs may 
read, or the practiced eye infallibly determine," but "there 
is grandeur in this view of life, with its several powers, 
having been originally breathed by the Creator into a few 
forms or into one ; and that, whilst this planet has gone 
cycling on according to the fixed law of gravity, from so 
simple a beginning, endless forms most beautiful and most 
wonderful, have been and are being evolved." 2 

1 After some months of such training as is outlined in the preceding 
exercises, the student should be prepared to take up with profit a study 
of the flora of the region in which he lives. In this way, with an indefi- 
nite amount of painstaking, independent, and long-continued work, he 
will gradually become more familiar with the systematic grouping of 
plants and accumulate for himself the evidence that more and more con- 
firms the conclusion formulated above. 

2 Darwin, Origin of Species, p. 429. 



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Elementary Science. 



T^atural History Object Lessons, a Manual for Teachers. 

By Geo. Ricks, Inspector of Schools, London School Board. Cloth. 352 pages. R© 
tail price, 1.50. 

Guides for Science-Teaching. 

Published under the auspices of the Boston Society of Natural History. For 
teachers who desire to practically instruct classes in Natural History, and designed to supply 
such information as they are not likely to get from any other source. 26 to 200 pages each. 
Paper. 
I. Hyatt's About Pebbles, 10 cts. VIII. Hyatt's Insects. $1.25 

II. Goodale's Few Common Plants, 20 XII. Crosby's Common Minerals and 
cts. Rocks, 40 cts. Cloth, 60 cts. 

III. Hyatt's Sponges, 20 cents. XIII. Richards' First Lessons in Min- 

IV. Agassiz's First Lesson in Natural erals, 10 cts. 

History, 25 cts. XIV. Bowditch's Hints for Teachers 

V. Hyatt's Coral and Echinoderms, on Physiology, 20 cts. 

30 cts. XV. Clapp's Observations on Common 

VI. Hyatt's Mollusca, 30 cts. Minerals, 30 cts. 
VII. Hyatt's Worms and Crustacea, 

30 cts. 

U^Qote Book. To accompany Science Guide No. XV. 
Paper. 48 pages, ruled and printed. Price, 15 cents. 

Science Teaching in the Schools. 

By Wm. N. Rice, Prof, of Geology, Wesleyan Univ., Conn. Paper. 46 pp. Price, 86 cts. 

Elementary Course in Practical Zoology. 

By B. P. Colton, A.M., Professor of Science, Illinois Normal University. Cloth. 
196 pages. Price by mail, 85 cts. ; Introduction price, 80 cts. 

First Book of Geology. 

By N. S. Shaler, Professor of 
figures in the text. Price by mail, 1 

The Teaching of Geology. 

By N. S. Shaler, author of First Book in Geology. Paper. 74 pages. Price, 25 cents- 

Astronomical Lantern and How to Find the Stars. 

By. Rev. James Freeman Clarke. Intended to familiarize students with the constel- 
lations, by comparing them with fac-similes on the lantern face. Price of the Lantern, m 
improved form, with seventeen slides and a copy of "How to Find the Stars," $4.50. 
" How to Find the Stars," separately. Paper. 47 pages. Price 15 cts. 

Studies in Nature and Language LessonSo 

By Prof. T. Berry Smith, of Central college, Fayette, Mo. A combination of simple 
natural-history object lessons, with elementary work in language. Boards 121 pages Price, 
so cts. Parts 1. and II. 48 pages. Price, 20 cts. 



By N. S. Shaler, Professor of Palaeontology, Harvard University. 272 pages, with 130 
figures in the text. Price by mail, 1.10 ; Introduction price, 1.00. 



D C HEATH & CO., Publishers, 

BOSTON, NEW YORK AND CHICAGO. 



